K2s in decent condition go for anywhere between £50 and £100+ here depending on a few factors:
Colour - black is rarer and more desirable, I'm told it was a special order at the time so most just bought a chrome one
Lens - mine was £50 because it only had an M 50mm f2 with it (since replaced with the K 50mm f1.4 like yours). The more unusual the lens the higher the price will be. I also had to straighten a bent top plate to get the hotshoe level again, give it a good clean and replace the light seals. A couple of hours work and I have a very presentable K2 which appears in full working order judging by test rolls.
There was a dedicated ever-ready case for the K2 which doesn't fit anything else (and the cases for the KX/KM won't fit a K2 as the tripod socket they attach to is a few millimetres further over), if you see one then buy it quickly as they aren't common. The front part is a pain but can be unclipped and left at home, the back makes the camera easier to grip and protects it from minor knocks. I can post a photo of the case to help identify them, the design is pretty distinctive. If you see a K2 for sale with the ERC then snap it up - generally cameras which have always lived in one had a very easy life although a CLA may be needed to deal with a decade or two of inactivity.
The K2 was launched as the professional model in the original K series lineup, with a price tag to match. There weren't many about to begin with, and people who have them don't tend to let them go (I'd only swap mine for an LX).
The K2 DMD is a different beast, rarer and more expensive as a result. I nearly bought one for £80 with some brassing and a non-functional self timer, but decided that it wasn't worth it and bought a lens instead. Had the timer worked I'd have pounced on it. See here to read what upgrades it has over the normal K2 and decide if it'd be worth the effort and cost to find one. I'd still like one but I'm quite happy with my normal K2 in the meantime.
You won't get an LX in working order for $100 or less, you pay roughly double that for a CLA for one here. You could probably get an MX but that puts you back on the cloth shutter - I seem to get decent exposures with mine and they've had no servicing beyond a cosmetic clean and new light seals. KXs tend to be a bit more expensive as they're rarer, but they do have MLU (as does the K2).
Last edited by PentaxBronica; 11-17-2012 at 04:19 AM. Click to view previous post history.