[9fans] Building my own gadget with Plan 9

[app]

I am toying with an idea of building my own MP3 player + general gadget
with Plan 9. Any suggestions for a budget HW platform? Can you make it
usable, with decent battery life? Audio out, USB2 in, some fancy input
device and a good display would be nice. Has to be small enough to fit
in a loose pocket.