There is no reason why you shouldn't: always check the sellers feedback reputation and make sure there is a clear return policy in place.
i don't see why not.. just be sure that ALL is included.. : i have bought a phone from someone and all i got was the phone and charger. when on the box it said : in this box there is : earphones, adapter, SD card, .. i got my phone. no earphones, i couldn't listen to music with earphones and since the tip was small a regular ear phone wouldn't fit. no adapter or SD card to save my music or pictures. i was still able to take pictures, but i couldn't save them anywhere except my phone..
you can buy a phone from ebay, just make sure they give you EVERYTHING.