It all depends. It's in very decent condition, it has box and papers.
To sell? I'd say $500. To sit at a table and be an ass about it? $750. It'd possibly even sell at that price. The internet has devalued the most amazing things and, more importantly, UP-valued other things to the point of insanity. Woodsmans and Diamondbacks among them.
NOBODY...and I mean NOBODY makes anything today that reaches the quality points of a Woodsman, with the exception of the Smith Model 41.
I like Mk IIs but they are an unwieldy pig compared to a Woodsman. All the plastic framed 22s are cheap...they are good for what they do, generally....but they are cheap shadows of the 22s of old.
If he wants to sell it ( and he's a fool to do so, as that gun is actually worthy of being an investment, though not in mint condition ) then the best way to gauge the value will be to put it at auction and let the market decide. Either way, he'll likely get a good price for it if he starts bidding at 500.
This is strictly one man's opinion, by the way.