Used is never a bad idea to gauge someone's interest in music. You can find a solid, well built used acoustic from 50.00-200.00 quite easily. Check out your local musician's trading post (the store will be named something similar, they always are) and see what's out there. A good thing to keep in mind though is how grown he is at 13, if he's still got lots of growing to do, and not the longest fingers, a full size may discourage him (it did me), and a 3/4 scale might be a better bet.
Used places thrive, and they're usually staffed with people who know their stuff whereas Guitar Center seems to be staffed with people who were deemed too stupid to work at Best Buy. And you never know, shopping for an axe might just get you in the mood to give it another shot....
