sam36 ,
uxcell.com sells the silicon skins for the 1.5" players. eBay has some sellers selling them, but i found uxcell to be cheaper when i bought mine sometime back.
You can use a normal ipod skin, but you would need to cut the screen to be larger (ipod nanos are 1.2"). Also the alignment of the buttons would be off too. And some clones have the earphone socket on the side rather than the bottom, for this, you'll need to cut the earphone hole too.