bought mine, a 6", for ~$400 plus shipping/transfer about 3(?) years ago, call it $450
no box, papers, crappy grips (which mattered not to me), but otherwise "LNIB" condition
I think SaxonP is probably right, not everyone is fond of the longer barrels
Prices have obviously not been on the drop since, but I think you might do $550-$650 on it, like rc said, if patient