It depends how much your time is worth. If you are happy waiting a week or three for delivery, testing it, going through the whole rigmarole of making a claim through PayPal to get a refund, all just to possibly save $10. Then go for it. But personally it isn't worth it to me. I'd rather go to a shop, spend a little more and receive something I can take home and use the same day I decided to buy it.
By the way I bought an SD card from an eBay seller in Australia, with 100% positive feedback, and who sold 3-4 SD cards a day - and it was fake. Either the people giving feedback were all naive and too unknowledgeable to use H2testw, or the seller had just started doing it recently (about two days after my negative feedback, there was another negative feedback similar to mine). After all that effort, I tried again with another seller and the same thing happened. Now it is about 5 weeks later and I still don't have an SD card. So I bought one from Officeworks for about 1.5 times what I was paying on eBay and had no troubles. After that I swore to stay away from eBay. Even if it IS going to be legit, waiting a week or two for it to arrive, and then overnight for H2testw to finish, isn't worth the savings.