If you want a portable mp3 player, here's one **broken link removed** The model Yampp-7 is the most up to date, and smallest, they also have one that runs of a laptop hard drive, and a few others they're all pretty nice, think the ones that aren't listed have been abandoned.
Also if you can't find all the parts for the Yampp-7, they have the full kit, and individual parts, at least I think they do... can't really remember... in the shop.
But It is kinda expensive, like going through 2 middlemans expensive, so if you can find the parts on your own, it'll probably be cheaper that way.