Back in the day, Nintendo used to hold their own 'Space World' events in Japan to showcase their up-and-coming hardware and software. They haven't held one of those shows in a long time, but a rare gem from one of the events has just popped up.
Somehow, a Space World GBA prototype has made its way onto Yahoo! Auctions in Japan, and is now in the hands of a collector. The prototype shows off different audio when you boot it up, and the L/R triggers don't have the same lip that you get on the final model. There's more subtle differences as well, which you can see in the video above.