If you are talking about the bolt carrier handle, I believe a new made bolt carrier handle is made, either through historical parts and militaria company owned and operated by Darrin Weaver, the author of the g/k43 book, or the part is through numrich(gun parts corp).
People like me have a spare bolt with extractor set and locking lugs, though right now I'd rather those get sold together, if I ever do even sell them, so my point is private individuals have some parts sometimes for that route.
NO, makes it a bitch to chamber a rd or clear a malfunction.
I would wonder at the mindset of anyone who would do that. Course it is also possible that they had the handle break - or come unscrewed and get lost and haven't been able to replace it. I just went to the shop and made me a new one when it happened to me.
What do you mean by "fair condition"??? Is it all matching?
With a butchered stock & missing cocking handle, if mismatched maby $1500. If matching then depending on condition maby $2K???
You'll be lucky to find a cocking handle so will probably have to buy an expensive bolt carrier. A good stock will cost you $400 +/-. IF you need a bbl band and retaining spring add another $100+