A friend has gotten into gunsmithing fairly seriously. I spotted a 16ga SW ejector at a local shop. Barrels were sound, gun was slightly off face, receiver was good, very poor restock job. That one was only a few hundred $, and by the time he'd finished with it, the major cost (other than sweat equity) being a semi-inletted stock, it was worth 3 times that.

Sometimes they're no-brainers . . . in either direction, go or no go.