When I still was into R/C flying, I was actually looking to buy a turbo-jet engine for a larger model jet. They started out around $2000 dollars and went up. And most of the turbo-jet engines were taking off smaller military missiles that were decommissioned and selling them. You could find them all over the place...if you had the money.
I love the sound of them turning up. Even though it still excites me to see them run, I have to avoid getting back into that hobby. We simply don't have any place to fly them close by.