Hi, i wouldnt really recommend buying from ebay especially unbranded mp3 players because you can get fakes that display 8gb but in reality they are only 500mb (Do some research on google about faking the mp3 player size).
I would however, recommend you to buy it from this retailer:
Yeh, i have used the website and recently i ordered a cowon iaudio d2. Their service is also excellent, infact, one of the chargers was faulty and they sent me a new one without any charge. You can also speak to them over the phone if you are unsure (plus they are a vat registered company!)