Well I bought one 3 yrs ago with a bender turbo and fully functional for $2000. They are junk in the mountains but can be a great deal of fun untill you stick it somewhere. I added wheels to the skid and ran it on simmons gen II skis in the yooper and i loved it as a part time toy on logging roads and mine pits in northern MN. Not sure there is much value to the parts - body work with carry over but the motor is the big ticket item running they sell from $1500 to $2,000 back when I blew mine up anyhow.
If you have never opened up one of these motors it is not a walk in the park. Tolerances are very close and if it dropped a valve you might be looking at more damage to the lower end. I blew 2 of these up and neither had a single part that was salvageable. cranks, rods, head, and block were destroyed. The only things left were carbs and starter. If it broke the piston I can almost gaurantee that at least the cylinder sleeve is wrecked.