I don't have experience with any tablet, but DW and I have spent A LOT of time looking into them. I have yet to see any decent tablet (IMHO) for less than an iPAD, or without a 2 year cell contract (no thanks). I believe any Android device can get the apps for the Nook and Kindle, etc.
I read an article recently about "rooting" a Nook, and basically making it a very good Android tablet, but it voids the warranty, can be tricky, etc. I am an IT support tech, and I don't even want to mess with that.
I am holding off until Viso comes out with their 8" Android tablet. They debuted it at the Consumer Electronics Show in Jan, and is supposed to be out in "summer". I think it's going to be called the Via, along with the phone version with the same name.
Sorry, I didn't answer your actual question about experience with tablets on eBay. Don't hate me...