I think $350 is fair. I don't know if it's *fantastic*, but it's definitely fair. They're real similar to Forte's, which usually go for more. I bought a pair of Quartets here on Bartertown for $300 and I love 'em.
I paid a few dollars more for mine in near-showroom condition & I don't feel I got robbed. So if these are in good condition and you don't care about the missing logo, then it seems like an ok deal. Then again, he says he has no use for them, so if you feel like haggling, make an offer.