Well, Raoul, you're the man when it comes to locating space imagery. Modern imagery is all digital and high-res is available online, so the period from the mid-90s onward is easy. It's the oldest material that's hard to find in high-quality/high-res scans.

You've probably already thought of contacting the ALSJ team to obtain high-res scans from Apollo. I've purchased film from NSSDC and scanned them at high-res, and played around with some enhancement. I'd be pleased to contribute high-res images if there's anything in my collection you want to use. Some images available on the Net:

Buzz Aldrin climbing down the LM ladder, enhanced to bring out detail in shadows.

Ed White's spacewalk enhancement.

Pirouette is a collage made from separate images of a Soyuz, Mir, and the back end of a Shuttle, recreating the scene from STS-71 when the Shuttle departed while Soyuz was on an inspection tour.

Now that I think about it, I have several dozen high-quality film transparencies (4x5") purchased from NSSDC, all from various Apollo missions, all scanned but not necessarily enhanced. Dozens more pieces of film from other sources of Mercury through Skylab, of varying quality. I even have a large reel of 35mm motion picture film containing Apollo 17 rover footage that I bought on eBay. (I'm very sure it's not original, but it seems to be a copy made right after flight for release to the media.) I've always wanted to get that film digitized, but digitizing motion picture film is expensive. But I digress...

If I can give you a hand, let me know, Raoul.