I'd start with Western Gun Parts in Edmonton, though they may pull the "you gotta be a gunsmith" line on you. They usually have a pretty good selection of used parts in hand, and the old guy there really knows what will fit what. The older lady that sometimes mans the phones can be a bit...brusque.

It help to have the gun in hand, and to be able to speak like you know what you are talking about!
Other than that, post a Want To Buy advert in the EE, in the Rimfire Parts and Pieces section.
Beyond that, it sorta pays to have gone to a bunch of gun shows and hoarded a selection of good contacts among the used gun parts dealers.
Expect to have to fit the bolt, easier if it does not close, as you then CAREFULLY remove a wee bit of material at a time off the back of the bolt handle lug until it closes. In the event that the bolt is too loose (excess headspace issues) you may need a talented welder to build it up and then fit the bolt.