Unless it's the last 15" model (1GHz CPU, USB2.0) and has a RAM upgrade, it'd be hard say $350 is a good price. If you're the seller and you can get $350 for it, that's great. But if you're a buyer, or if you're an owner and you're trying to figure out how to price it, I'd say $300 max unless it's got unusual upgrades or extras. For an older 15" model I'd say $250 is more realistic.
M