As well as EasyCE there's PocketFrog and GapiDraw also with forums on this site.
If you want to write music software to handle your samples you may not need to get into GAPI programming ( which is a way of getting direct access to the screen )
You can try e-bay for a 2nd hand iPaq h3650 color device or perhaps a similar HP pocketpc. Make sure you get one with an ARM processor & not the slower MIPS / SH3 unless cash is short. If you can't affort the iPaq for for one of the Casio devices from a couple of years back.
