I bought a 640-1, no lock, LNIB, for $500 in early March. Mine is from the first year of production. I’d say values on these in like new condition would go $400 on the low side and it could be anyone’s guess on the high side. I haven’t seen one for sale in the PNW for under $500 for years. Before the one I bought, the only one in a year I found for sale was a safety lock Model with some porting work for $800.