It looks to be in "very good" condition, so I think $350-375 is a bit light. I have a "very good" 3" model 36 (same tapered barrel as this airweight) and I just made a deal tonight to sell it for $400. The 37 is less common than the 36, and a 3" barrel airweight seems to be even less common yet. So I would put the value more like $400-450, at least in my area- or I would if it had the stock s/n'd magna grips instead of Pachmayrs..
Personally I prefer the 2" (that's why I' selling my 3" 36), so the barrel length would not be worth a premium to me (quite the opposite).