There is a LNIB 2" 631 on GB right now with a reserve that has not been met and a $1500 BIN. Maybe your seller has seen it and considers his price to be a bargain based on that?

Over the past year I have acquired a 631, 631 Ladysmith and a 632, all great little revolvers. Got the Ladysmith cheap and the other two at what I considered to be decent prices. Passed up a couple that I thought were overpriced along the way, just kept looking and tried to stay patient.