Uh, I don't really have a collection of anything really. I have a few items that you don't see every day but they aren't super rare or anything.

Let's see...

Osu! Tatake! Ouendan! for the DS. It didn't sell in huge numbers in Japan but is quite easy to find on eBay or through an importer. Probably not something many people in the UK will have heard of or seen.

A Ford Racing Puma. They only made 500 of this particular special edition Puma and a fair few have been trashed, but there are always a fair few for sale if you look on enthusiast sites.

Um, stretching it a bit now but Ikaruga for the gamecube and the DVD of the proper French versions of Taxi 1 and 2 not the recent crappy American ones.