The difference is the difference in the two markets. Ebay is more of a vintage, oldie market, while Audiogon is home to the more "diehard" audiophiles, IMO. For example, Dyna st70's, not working, go for like $200 at ebay. Mac stuff, seventies receivers, and mid fi like Adcom fetch rediculous prices at eBay, while Agon'ers would have a tough time with that stuff. Meanwhile, the more recent, highly touted high-end gear does better at agon. bottom line, if you can get one for a lot less at ebay, jump on it. If I was selling an M3, I would not list it on ebay, because the buyers there don't really know it.