Should do the job nicely
Also note, using your own socks is probably better, and cheaper >.>
But to be somewhat serious, buying cases of other mp3/4 players should suffice.
If you wanted a case where you can do your touching, I would've suggested a Ipod Touch/Phone case, but studies show that the Onda is a bit too small and a bit too thick.
You can try looking for cases for PDA's and the like. Websites of popular retailers like Bestbuy or Circuit City can give you a good insight on some cases.