I've had great success with eBay using my PayPal account. What I did was to browse the listings carefully looking for private owner listings claiming lightly used units with no scratches that were always (as an example) used with a screen protector and inside the factory case. Here are some examples of my purchases.
iPad 32 GB with ATT wireless and Apple leather case. This was barely used, shows no scratches or defects and the seller included the original Best Buy receipt. We do not use ATT so I just turned off the cellular wireless.
iPad 16 GB came with Apple docking keyboard and two extra screen protectors. Again, perfect condition with no scratches or defects.
I also got my wife a Toshiba Thrive Android in perfect condition with Toshiba leather case and screen protector.
All three arrived with free shipping included within several days of the purchase. The Toshiba was around $165 and the iPads were around $220 to $250.
I seem to have good luck watching listings on holiday weekends when more people may be out doing things other than watching their computers. I type in the maximum I am willing to pay and only bid when there are about 20 seconds left on the action. The system increases your bid like $2.50 at a time so you only pay your maximum if you are continuously outbid.