I bought a PSP on my first trip to Japan in 2008. I think it was around 30k yen. I remember the store I was at had used ones labeled with which firmware version they had, and I got a slightly more expensive one with an older firmware (3.4.0?) because it was one that had some vulnerability that involved a specially crafted save file for Lumines that allowed installing a custom firmware.

It was(/is) a great device for playing ps1 and snes games. It doesn't seem so special now that there are so many emulation focused handhelds, but at the time it felt really awesome to be able to play games like that on a plane.