"Now if only I knew how to find these fish I'd save a lot of money"
You just buy a fishing license, find a legal fishing spot where the species you want is known to occur, and then go out with a seine or a dipnet. Very easy, at least here in North Carolina. I guess in Florida you have to worry about alligators :(

The people on the NANFA forum can give you some tips, like how to use a seine and how to add salt to the bait bucket to increase fish survival.

"Not sure if the local stores will have all of these, I hope they do. If not I suppose I could order some from the site I found them on. "
Liveaquaria.com is a good website, but you should compare their prices with aquabid.com and thatpetplace.com. When different vendors compete, you win.

"I also need to do a little more research to see if sand substrate will suit all of them, as that's what I'd prefer."
Yes, sand is fine. The major downside to using it isn't that fish don't like it, it's that a single grain of sand in between your magnetic algae scraper and the glass wall of the tank can scratch it up in an instant. It also can compact over time and make these gross black air bubbles that smell like death. It's not that fish don't like sand, it's that people don't like sand. I personally use kitty litter, as in the pure ground baked clay with no clumping chemicals added. I like it very much.

"So I've done some looking around and these are the fish I think I've decided on ....Neon/Cardinal Tetra's.... A male betta... Topsail Platy.... Celestial Pearl Danio... Zebra Danio... Turquoise Danio.... Otocinclus "

Here is my suggestion based upon the seven fish species you listed above.
1 male betta
5-7 of either neon/cardinal tetra or one of the danio species
4 otocinclus
and maybe a platy or two or three. Go with all males, because you don't have room to breed offspring in that tank.

Otocinclus are schooling fish in the wild. (http://www.youtube.com/watch?v=ilnitMs1LRk )
So are most danios, and so are tetras. That means that you'll want to keep either zero or five or more of them. A lone schooling fish is usually an unhappy fish, and lone danios and tetras are fin nippers.
The school should dissipate the aggression and prevent the tetras/danios from nipping the betta's fin too much. Contrary to popular belief, it is the betta that must be protected from other fish. They're famous for their aggression, but in real life it's more common for them to be ripped to pieces by their tank mates than the other way around. So keep an eye on him and if the tetras/danios start picking on him, get him his own 5 gallon tank. Poor thing.

Also, I should probably tell you that I personally don't keep algae eaters. They're overrated. They won't eat all of your algae, so you'll have to do some tank maintenance anyway. The soft magnetic sponges and the algae eater both let those little green dots appear over time. So if you're getting the otocinclus just for their role as algae eaters, you might want to reconsider. There is no substitute for a good scraping of the glass once a month with a credit card.

So. This is the part where tank design comes in. Do you want a tank packed full of fish or a tank with only a few fish? If you choose the first one, then you're going to have to accommodate an increased nitrogen load. This means that your tank has to convert more ammonia than other tanks would. Usually my best suggestion for getting that done is having live plants in the aquarium. Since you don't like that, you could alternatively add an extra sponge to your biological filter and then perform more frequent water changes.

There is kind of a spectrum of fish maintenance. One the one extreme, you have the heavily planted tank. For example, this is my 55 gallon tank, which had such a light fish load and such a large number of plants that it consumed nitrogen faster than it produced it. The moment even a drop of ammonium was excreted as fish waste, the plants gobbled it up. Nitrate was always between 0 and 10 ppm, even when I didn't do a water change for months and months.
http://www.youtube.com/watch?v=k3ikKTwTEKs

On the other side of the spectrum, you have your completely unplanted, heavy fish load tanks. These tanks rely upon the beneficial bacteria to convert ammonia to nitrite to nitrate, and then upon the fish keeper to perform water changes to dilute the nitrate. It is the most work intensive style of fish tank. Instead of the previous scenario, where the nitrate was constantly less than 10 ppm, this scenario has drastic increases in nitrate. Over the course of one to two weeks the nitrate may rise from 0 to 40 ppm. With no growing plants to serve as nitrogen sinks, the only way for nitrogen to leave the closed system of the aquarium is by water changes. Whereas the first described scenario can handle more fish being added to the tank, more fish added to this second scenario would overstress the system. Overfeeding this kind of tank can cause an ammonia spike as the already overworked biological filter struggles to compensate. The ammonia spike goes unnoticed by you (it is a clear, unnoticable chemical) and the fish start becoming poisoned. All you know is that one day you wake up and your fish are diseased, when what really happened is that poor water quality forced them to succumb to some pretty harmless pathogens that were always present but that their immune systems were normally strong enough to fight off. That one day's overfeeding can turn into a huge problem.

So I guess my point is, you can never have too much filtration. Extra filtration places an overstocked tank in the middle of the spectrum instead of at the dangerous extreme end and prevents ammonia from accumulating suddenly and causing fish death. Extra filtration is good. What I do is, I go to my local store and buy synthetic sea sponges. They're like three bucks and what they are is a chemical free sponge, no soap pre-added. Sponges have massive surface area, which is great because that is where your beneficial bacteria live. Then I stick the synthetic sea sponge on top of the existing filter media. The water is forced to flow through the sponges, so after a while they get colonized with beneficial bacteria. It adds more homes for your beneficial bacteria to live, increasing their population, and increasing the strength of your biological filter. For tanks around 55 gallons or more, I recommend going with a fluidized bed filter. This source says that fluidized beds have more than 6,000 square feet of surface area per cubic meter compared to a waterfall filter's 200 square feet of surface area per cubic meter. http://www.bioconlabs.com/abtqs.html

You might want to think about having maybe one live plant in the aquarium. If there's an ammonium spike, the plant will eat it. Look at table 2 on this page: http://theaquariumwiki.com/Plants_and_B ... Filtration It literally only took water lettuce 31 hours (that's less than two days) to absorb 3.2 mg/L (same thing as ppm) of ammonium. So before you can even notice a problem, it has taken care of it. Nice. Good plant.
So having a plant in the aquarium, even just one, is a good security measure.

If you overcompensate for the amount of ammonia that will be produced by your fish, and if you have a safety plant in there to protect them in the instance there is a nitrogen spike, then I don't see why you can't heavily stock your aquarium. You just have to plan for it beforehand and realize that you're heavily stocked. Keep up on the water changes. If you start seeing diseases pop up, it's probably because your water's dirty. If you get sick of doing a quarter tank water change every week, then maybe you'll find yourself wanting to have a more planted aquarium. Your opinion about plants might change.

Here is a photo of my extremely heavily stocked 10 gallon with guppies in it. There are 15 or 16 female guppies and 1 male guppy (it's a breeding tank). Because of all the live plants, the water stays clean. I had some bad times one week after the filter ran dry for a few hours and all the bacteria died. That's how I know for sure that the bacteria and the plants are both working together to keep this tank's waste controlled.
This picture is really old, though, doesn't show the 15 females as adults. http://img.photobucket.com/albums/v415/ ... pytank.jpg Hmm, maybe I'll take a new photo when I get off work today.
(Edit: here's the new photo of what it looks like now. All the green protects the babies. http://img.photobucket.com/albums/v415/ ... /014-5.jpg)
Anyway, you get my point. Heavily stocked tanks are possible. They just have to be planned for in advance. And you're taking a bit more of a risk with disease. Feed lightly...

Lol, Natalie, you beat me to it. I was editing my post to include a warning about bettas getting their fin nipped as you typed that. XD
I have such long posts sometimes that it takes me a while to edit everything. *blush*

Female bettas are very hardy in my opinion.

I have had mine for over a year now without any problems.

It has survived numerous fish tank disasters.

Java fern, crypts and anubias do great in low light situations. Cryps are one of my favorites. I use them in my high tech tank too. I've only used flourescent lighting, so i'm not sure if that makes a difference.

I use eco complete in all my planted tanks. It is expensive, but i like the way it looks and it seems to be a pretty good all around substrate. The plants that you are looking at aren't really picky about their substrate. in fact, anubias and java fern shouldn't be planted at all, but do best when grown attached to driftwood. Crypts can be grown in regular gravel, but flourite would probably be beneficial.

"Does anyone here use Flourite plant substrate, or have any knowledge of how effective it is? I like the idea of not having to worry about fertilizing the plants, plus I kind of like the natural look of Flourite."

I wish I'd seen this post back when you wrote it. Kitty litter is better than Fluorite(TM). It has the same initial nutrient content but also has a high CEC (cation exchange capacity) so it will keep that nutrient content over time and not wear out like Fluorite(TM) does. More information: http://www.thekrib.com/Plants/Fertilize ... jamie.html
The brand I use in my tank is "Special Kitty" cat litter from Walmart, $4 for 25 pounds. It is pure baked ground clay, no added perfumes or clumping chemicals.

Also, it's better to use full spectrum light bulbs to grow aquatic plants. The reason why is that the chlorophyll in plants isn't able to absorb energy from light that is 500-600 nanometers in wavelength. Image: http://upload.wikimedia.org/wikipedia/c ... ectra2.PNG
With a not-full-spectrum light, the light may be emitting useless energy the plant can't access. So get a full spectrum light bulb, because that way there will be at least a few peaks at the wavelengths of light that plants can eat (400-500 and 600-700 nm).