If you can find a clean iriver H120/H140 you'd be all set. The battery can be swapped out if necessary, mine gets 16hrs on a full charge on playback of mp3's, roughly 8-10 hrs on recording wav. Mind you, its a 16/44 recording device. It also features analog line/out, optical in/out. You have to rockbox it to really appreciate its recording features though (not a biggie) and you can control left/right channel's independently with rockbox.
It's also small (ie. pocket-sized).
edit: oh, its not flash, its HDD-based.