I picked up a NIKKOR-S 50mm / 1.4 from KEH for only $69. It's a sweet lens that you'll find parked on my FM3a 99% of the time. It's a great bang for the buck!
I normally shoot 8x10, BUT when I have my FM3a in my hands it is usually for the SPEED of 35mm. Having said that, I want the fastest lenses on my Nikon. The f1.2 costs a few $$ more, but it is still CHEAP compared to what they cost when new. Watch Ebay and you will be able to find one for less than you paid for the body.
Henry,
I have the Nikkor 50 mm f2.0 AI lens since 1978 and I have to say that it's very good.
One thing that hasn't been mentioned as yet and I would concede that it is a small point but may be important to you is that traditionally AIS lenses have a shorter focus throw than AI lenses. The 50mm f2.0 AI has a throw of 230 degrees while the 50mm f1.8 and f1.4 lenses have a throw of 130 / 140 degrees.
I have a FM3a and I'm presently looking for a 50mm f1.4 AIS to go with it.
My opinion is that you need to get a lens that feels comfortable with the camera and gives you the best from the camera and in my view that is the f1.4 AIS and if your budget doesn't run to that get the f1.8 AIS.
I noticed a recommendation for you to look at Bjorn Rorslett's site which is excellent and this one is also quite useful - http://www.photosynthesis.co.nz/nikon/specs.html
Hope this helps
Best wishes
I have both MF and AF Nikon 35 mm bodies. I have both 50mm afd and 50mm f/1.8 AIS. The auto focus lens doesn't not focus as smoothly. the ring is smaller and more difficult, for me.
I would get a 50mm f/1.8 AI or AIS. KEH has them and you will find them great to deal with. Do not be afraid of their BGN rated equipment.
Another vote for the Nikkor-S 50f1.4... If your FM3a is a chrome body, the chrome barrel of the 50f1.4 will provide the "look". It also performs pretty well, in my experience. The single coated glass seems to have more contrast than the first multicoated version, that being the Nikkor-SC 50f1.4, and seems to provide the same contrast as the AI version. I have two of these lenses. One with the factory AI modification done, and one that's still non-AI.