The newest 10/22's have a plastic trigger guard that some folks don't like, and the reciever has a crinkle finish that also is disliked by some. If your friends rifle is an older one with the alloy trigger guard, and the nicer anodized reciever, it is worth, in my opinion, the cost of a new one at retail price. Also, there are quite a few different models, the regular carbine ( least expensive ), the DSP with checkered walnut stock and no barrel band, the Target ( heavy barrel, laminated stock ). Value will vary.
Mark