I recently bought a somewhat old convertible tablet PC for $65 USD on eBay. The Fujitsu LifeBook P1630, which was originally sold for more than $2,000 USD back in 2008, is a small laptop/tablet PC with a 1.2GHz Intel Core 2 Duo and an 8.9" resistive touchscreen display (1280x768). Size-wise it is similar to the netbooks (like the Asus Eee PC) that were starting to get popular at the time, but it is definitely much more powerful than the early netbooks (and also much more expensive at the time of its release). Although it was originally sold with Windows Vista (and mine came with Windows XP Tablet PC Edition), I immediately decided that I would put Linux on it, partially because I was curious about how well Linux would work with a touchscreen (Android doesn't really count). Speaking of Android, the P1630 is a bit different from modern tablets: Like other older tablet PCs it has a resistive touchscreen instead of the capacitive touchscreen found in smartphones and most post-iPad tablets. This means that the touchscreen can only be used with sharp objects, like the plastic stylus that comes with it (or fingernails, but that feels a bit awkward).
The unit I got was in pretty much perfect condition, and doesn't have any visible scratches or marks on the case. It certainly doesn't look like an 8 year old computer, so it probably hasn't been used much. The only problem listed in the eBay listing was a BIOS password unknown to the seller. I decided to buy it despite the BIOS password, since I assumed it could be reset one way or another (and I was right). It also didn't come with an AC adapter, so I had to throw in another $10 for an unoriginal AC adapter from China.