I think this is a very good question. Here's the deal. If you have a healthy and wise ( not a smartass but wise ) LFS owner, then he or she probly have some good lookin' live rocks in store for ya'. 10.00-13.00 dollars/lbs., but you'll go like W O W!!! Full of purple, red, orange coralline algaes on them, maybe some oyster growing on them if you're lucky. Those colors on the rocks are there because the owner knows what he's doing. DO NOT BUY THOSE ROCKS WITHOUT EXPERIENCE!! You'll take them home put them in you cycling tank, and that's it. Been there done that. All those beauties on the rocks will start to die off, and that can kill your soul. BUY THOSE ROCKS WHEN YOU HAVE A MATURED WELL CYCLED TANK. Water parameters are also very important matters. If you put your rocks onto a FO tank, you probably never paid any attention to calcium or magnesium levels, which is alright. But when it comes to live rock, you suppose to watch you CA at least. With good Mg level would be even better.
I'd recommend to buy live rocks online, specially if you are about to start a new set up. When you'll receive those rocks, you'll might say"Damn there's only few purple spots on them, nothing like the one's at the LFS"but it's all good. That's why you paid a bargain price.Let see how good aquarist are you? Can you multiple those purple spots? You should, if you can't you're probably not ready for those beauties at the store. It is so awesome when you wake up in the morning and you find "fresh" coralline growth on your rocks or glass, so you know you're on the good track. Also never introduce those "online rocks" for a matured healthy set up. That's when you have to pay the high price, from a healthy source. My point is, rocks bought online ( good source petsolutions.com, foster and smith's ) perfect for a new set up, or start wuth. Otherwise cure them before you put them in your main tank... GEEE!! I GOTTA GO TO SLEEP!!! Next time slap me..:-)