I've purchased several fish from my local Petco. They typically have common fish, and I've actually had better luck with Petco than some of my LFSs. My yellow tang, coral beauty, and scissor tail damsels came from Petco. They were very thin and ragged looking, but a couple months of fattening them up and they are happy and healthy as can be. The scissor tail damsels spawn constantly. Sometimes they will have some uncommon wrasses or even occasionally a rare one. Once saw a Labout fairy wrasse and the price wasn't terrible, but it was on its way out. If I had been their earlier, I might've been able to save it.