I bought my SGI from him (and another board, IIRC), and while it wasn't cheap, it wasn't exorbitant. More importantly, it was clean, fully functional and exactly as described.
BTW, the lettering on the black AT-101W, if you're buying it used, may appear worn, but the brand new ones aren't much different from most of the used ones I've seen. Even NIB, the lettering appears weirdly faint.