Hi Rocco, I am like you. I have an older K100d on its' way to me. I have an intro being approved by the mods that explains my reasons for the K100d.
Re lenses, I am researching which older lenses will fit the K100. On the NZ national auction site there are a number of well cared for cameras with lenses under the 'Film' banner that are well under the asking prices of the equipment posted in the digital sections. I will probably just stick with the original lens while I learn the camera, but it is tempting to chase a camera that is in mint condition and starts at $1 no reserve.
This is an example.
Pentax SFXn SLR | Trade Me