simple - do not buy from ebay
or if you do then check here first on the bad sellers list to see if they are a bad seller
i would recommend trying these sites for cheap player as they have good customers service and will NOT cheat you
www.uxcell.com
www.dealextreme.com
www.mp4nation.com
www.houseofdap.com
www.kaidomain.com
this is a few to try, mp4nation and house of dap sell more well known chinese randed players so are a bit more expensive but are better quality, the other mainl ell really cheap no brand goods, but all are good sites