Well if the one at petsmart turns out to be a male then 250 is over priced, if it turns out to be female then 250 is a decent price.
Also as many have said before buying a snake from a petstore to 'save it from its living conditions' is somewhat futile. All the store sees is that "hey ..people are actually buying these things at that price, lets restock".
Then a week or two later theres yet another snake in there in same conditions.