I've bought some parts for a couple machines on my wish list--only because they were for a good price and weren't being reproduced. I certainly won't pay top dollar for parts for machines that I don't have, since I'd rather put the money into the machines that I do have.
So far, I've been surprised at some of the unusual finds I've managed to acquire, so I imagine my "wish list" pins will pop up eventually for reasonable prices I'm comfortable with.