If you fancy owning an older camera my tip is to buy one and then wait. Works for me. I've had my Sigma DP2S for a while now. I bought it ultra cheap off eBay some years ago. I think you can get them even more ultra cheap now, which is unfortunate for me, but good news if you fancy an interesting camera to have a play with. This weekend I got it out to have a play with again.
The Sigma uses a rather strange Foveon sensor, which means that rather than combining adjacent Red, Green and Blue pixel information it has a multi-layered sensor which grabs all the colour intensities at one spot. This makes for sharper appearing pictures even though the actual resolution of the shot is modest. The camera also has a rather nice fixed lens.
The biggest problem with the camera is that, compared with modern devices, it needs a lot more light to get a good quality picture. The good news is that when you get a shot, it looks very good, on a par with much more expensive cameras.
Sometimes, rather than spending a huge amount on an expensive, state of the art, camera it is fun to spend much less on something that has been around a while. If you choose your supplier carefully (eBay feedback is important here) you can get some quite fun devices to have a play with.