The GP32 is very much fun in direct sunlight out in the summer. Look for used cards on ebay - I doubt anyone still manufactures them...
and be prepared to order a MMC card READERas well, too; the GP32-USB-cable, if it´s part of your set, is no more supported nowadays; so you may need a card reader for drag and drop.
With a multi card reader, you can drop homebrew games onto the MMC-card even by the Pandora