You really don't want Non-AI lenses for the FM2. The camera was designed to work with AI and AIS lenses. I don't know where the idea that early non-AI lenses are selling for very little money got started either. Sure you can find them, but good examples fetch pretty good prices on par with their AI, and far more convenient to use, counterparts. To use the older, pre-AI lenses, you need to flip the metering tab on the body out of the way and use stop down metering. If you forget to flip the tab out of the way, and you try to force a non-AI lens onto the body, chances are good that you'll break something. Human nature being what it is, this will happen and any money you might have saved by going for the least expensive solution will evaporate into a repair bill. Add to that the fact that stop down metering, while not hard to do, is a pain in the ass, and you've got some really compelling reasons to NOT use pre-AI lenses on the camera.