Sorry this reply is so lengthy... There are still great deals out there on these lenses. I am a huge fan of m42 lenses, have been ever since a pro photographer I used to know gave me a Spotmatic many years ago. So, I have a Pentax m42 bellows and adapters that will let me put it on either my Nikon or my wife's Canon EOS (35mm). As a result I'm always on the lookout for lenses that will fit, and I've found them in some interesting places. Large antique malls - the sort that have many individual vendor booths - often have at least one vendor who deals in cameras and there are almost always a few screw mount items there. I found a Novoflex 105mm bellows lens for $25 this way, and also a complete Pentax S2 Super kit with two 55mm and one 135mm Super-Takumar lenses for $75. Also, if there is a "real" camera store near you, the kind with "junk" bins, it's worth it to have a thorough look - I've found some nice lenses this way as well, including a very nice Super-Lentar 35mm f/2.8 for $5. Finally, check local Craigslist ads and your local Goodwill (also check shopgoodwill.com) because these things turn up there all the time and often go for a fraction of their value. Finally, some people are literally giving them away: the college where I teach recently received in donation a nearly-pristine, working perfectly, Pentax Spotmatic with a Super-Takumar 55mm f/1.8.
Originally Posted by Lauris