To come up with one at a decent price, you'll probably just have to be patient. I got one about eight months ago after searching Ebay for a few months and even putting a Wanted Ad on this website. After finding one, a member on this website "flyingpalm" contacted me and said he had one for sale. he might still? Using a 19/3.5 FL Canon on 7SZ.
Good luck, I think I ended up paying $40.