I'd suggest, as an alternative to the FM2, which is usually higher priced due to demand, to look for a Nikon FE or Nikon FE2.
The FE2 was one of the best 35mm SLRs i've ever used. Same for the FE which i have the pleasure to own. Don't be put off by the fact that they use batteries -- they require just two small SR44 batteries which last a lot (many months), and they are extremely reliable cameras.
Additionally, the FE (not the FE2) is able to mount pre-AI lenses, which is a big plus, in my opinion.
I also own the Nikon F3 but i can say the metering electronics are not too reliable. The meter died on my F3 and my friend's F3 also has electronic problems. Same for the Nikon FA. In my opinion Nikon got their electronic cameras reliable starting with the FE. On mechanical cameras the best, and by far, is the Nikon F. But the Nikkormat FT2 can be had for cheap, uses modern batteries, is reliable, and mounts all Nikon lenses.
As for the Canon FD system, don't overlook that system! Lenses are excellent (on par with equivalent Nikkors), and some of the cameras are very nice. I'd recommend any of the following:
- Canon F1 (obviously)
- Canon FT, FTb, TX, FX
- Canon EF (amazing camera)
Additionally, the Canon T70 is a very capable camera, although it is one of the ugliest cameras ever. The T90 was the most advanced FD camera, but prices are high for examples in good condition.
I'd say, get yourself a Canon FTb and be happy. Lenses i'd recommend for the FD system are:
- the 17mm f4 lens
- any of the 24mm lenses
- the 35mm f2.0 lens with concave front element
- the 55/1.2, 50/1.4 (all versions), and the plastic fantastic 50/1.8
- any of the 135mm or 100mm lenses
In any case, you can have a very cheap and useful kit with the 35/3.5 FD lens, a 50/1.8, and any of the 135mm.
On Nikon, best prices (best bargains) are with the pre-AI lenses; the classic Nikkor-S 50/1.4 is very good, for example. Nikkor lenses are consistently good save for very few exceptions.
As for the Minolta system, if you can get a XE camera then you'll be very happy. I'd say that's the high watermark of Minolta, save for the XK professional camera which is very rare. The SRT-101 is also easy to find and a good camera.
Stay away from the Pentax K1000, it is currently overpriced and overrated, because it doesn't bring anything special to justify it's price. Go for the Spotmatic instead, and screw-mount Takumars.
Olympus system is very nice, the OM-1 is a very nice camera. However, i have reasons to think most Olympus OM lenses are slightly lagging in optical performance due to the need for them to be as compact as possible. The opposite is true for the Zeiss Contarex lenses -- they made them as big as they needed to be; optical quality was consideration #1. For example i found the OM 55/1.2 a very poor performer while my FD 55/1.2 was fantastic (and significantly bigger and heavier). So you'll have to look for reviews before buying a particular OM lens.
Stay away from the Rollei SL35 and similars.
Contax RTS system -- if you can afford it, go for it!! But the best kept secret in 35mm SLRs must be the Yashica FR-1, which is related to the RTS.