They are rare to get your hands on to be honest. @stevemen will be your best bet. But if not, it's going to be a case of looking on Ebay for anyone breaking one to see if they have one. Failing that, you'll need to hit the Japanese Auctions like Jauce.
You can gut the pop up tray of all the xanavi display gear, and end up with a bin & lid, which will still spring shut if you leave that bit in place (I've done this) - although it would need a little 'handle' to allow you to open it without using a screwdriver !