Depends on what you are looking for, how much money you can spend and all that. You can always check out here as a start: http://www.therpf.com/junkyard/
That said, 14 is a good age to get started on some of your own projects! Enlist a parent to help you with some of it as something you can do together, maybe. My nephew is 14 and just started working on some stuff of his own in foam. He's not allowed to use power tools himself until he's 16 but there's a LOT of stuff he can do.