If you have to have a quad G5 for whatever reason (collecting, whatever) -- then I suppose any price you're willing to pay is the right price, but I'm on the "there are far better computers for $380" train, myself.

Hell, the new chromebox will outperform most if not all of the G5s, computationally, at this point, and its OS will be receiving updates for at least two years, depending on if Google/Samsung can sell any.