You might try connecting with a group of astronomy enthusiasts near you, Morten, and see if you could arrange to borrow/rent one of their telescopes, or just get some shots by attending one of their sky-watch sessions. All you'd probably need to buy would be a T-adapter for your camera (Canon and Nikon are common).

The 8" Celestron, for example, is about 2000mm, producing a moon image of about 20mm on film (any format, so 35mm film is fine). As a tele lens, it's not as sharp as one might hope, but it's better than trying to enlarge a smaller image too much.