Thanks. I got the shell from China for $13.20. It came with black buttons, a new screen protector, silicone conductive pads, hinges, and screws. The only downside is that it took 2 weeks to get to the U.S..

Not gonna lie... taking it apart and putting it back together in its new shell was a pain in the @ss. Took me 2.5 hours to do it because I kept opening and closing it every time I realized I forgot to put something back, or when I realized I was missing a screw. And the hinges were the biggest pain.

Shell here:
Transparent Blue Clear Shell Housing Case For Game Boy Advance SP GBA SP | eBay