A year ago I think Ben is correct...they were about $150 then. That is no longer the case (at least based on my experience).
In general K Frame SQ tend to fetch less however N frame SQ are not as common and seem to be on par with their RB N brothers in the current market. My opinion only however I have yet to see a pair of SQ N Frame combats for sale at $150 (used less in mint conditition). Good luck out there.