I don't think EB and GS still carry N64 systems, although I still did see some last spring in store. Gamecrazy's still carry N64, they get them in quite a lot, now that the idio...I mean nice kids are willing to trade in N64 with games and first party controllers for Grand Theft Crap. Also, I'm not sure whether your town has it or not, but Toyriffic carries everything since the 80s, though they use Ebay pricing (but they are private, so you can haggle). And even though others may suggest it, avoid pawn shops, unless you can trust them or know them. They don't offer refunds so if there are some N64, you pick the best looking one, and it happens to not work, what do you do - exchange for the crappy one?
Last recommendation, the only good recommendation: buy a CIB (non-mint!) N64 from an Ebay non-store member with strong 99-100% positive feedback.