I believe I have a complete, mostly in box, collection of Game Boy accessories, but I may be wrong. I'm always on the look out for that stuff.
The only other thing I am working on is the Sega Saturn collection, though very slowly now. I have a very nice copy Panzer Dragoon Saga, but there are still a bunch of other spendy titles. The next expensive one I am picking up for sure is a copy of Albert Odyssey, I really want to play through that.