I think the petco's are hit or miss as far as quality of fish is concerned.
I've never had a single fish die that I got from the Petco here.
Currently have a GT that I got from them at 2.5" and he eats like a pig and is up to about 4" now.
As for price of these, I wouldn't really worry about it. It's going to be between free and $10 for a juvie depending on where you get it. They're really cheap, and if you find a good one, just get it. You're talking about a $5 swing in getting a "good deal" vs. a "bad deal" on these. And over the span of the fishes life, thats nothing.