I haven't bought an M in at least a year, but I got the impression that good ones have been selling in the $50-70 range + shipping.
This looks to be a clean, tested, complete early 1391401 model with heavy plate and PS/2 cable at the very low end of that range.
When 52Gs and 92Gs are selling at similar price points, this one is far more desirable, in my opinion.