Maaan, I´m in the same situation as you... Well, sort of. A couple of years ago I gave my little brother all my Amiga stuff (A500, A1200, harddrive, 68030 accelerator, lots og games, INCLUDING both Space Crusade AND the Expansion).
I thought he would have fun with it, but he sold it shortly after. I don´t think I have completely forgiven him yet :-)
Anyway, now that emulators have started appearing, I have bought the Amiga Forever Pack and have slowly started playing the good old games again. I am really anxious to get a hold of the Space Crusade Expansion in adf-format, either for buying or downloading.
Please, if you have it, could you contact me?