Keep in mind that the babies at Petco are mostly stressed out from being poorly kept there.
My local Petco has 10 babies in one enclosure, all striking. They aren't mean, they are scared, and not offered proper hides (usually just have one HUGE 1/2 log hide).
I asked to look at one the last time I was in there, and the reptile person was too afraid of getting bitten and I had to reach in and get the one I wanted to look at myself.
For the same amount of money as buying one from Petco, you can find a well-started captive hatched or captive bred snake (including shipping).
Will Bird has some here: http://www.ectotherms.net