No one makes 35mm film cameras anymore.
If you want really high-quality images, consider going with a medium format camera like a Rollei-Cord, Yashicamat or a Mamiya. Down side to these twin-lens cameras is that you can't change lenses. But the increase in negative size make a huge impact on image quality. Twin-lens cameras are perfect for landscapes, portraits, weddings, and still life photography. They are not recommended for anything moving such as sport & wildlife, nor are they good for macro work.
You will want to buy from reputable retailers such keh.com. Keh.com is IMHO the best place to buy used gear. They always under-rate the condition of their gear, so you always get gear in better condition than expected. They provide 6-month warranties and provide in-house repairs if needed. They have a good refund policy, too.
Ebay.com is a great spot to buy used gear, but you better know what you're getting into so that you can ask the right questions.
Buy the SLR that meets your technical photographic needs. Unlike DSLRs, an SLR cannot have any influence on image quality. Once the shutter button is pressed, there's literally nothing but air between the rear element of the lens and the surface of the film. It's physically impossible for a $2,000 35mm SLR to produce sharper images than a $50 SLR with the same lens.
Some auto-focusing SLR recommendations:
Nikon N8008s, N90s, F100, F5 (Avoid all 4004 models)
Canon EOS-1, EOS-3, EOS A2 and EOS Elan II (skip the "e" models).
Some manual focusing SLR recommendations:
Nikon F3, FM, FM2, FE, FE2
Canon T90 is the best manual focusing SLR they ever made - period. The T90 was used by professionals such as photojournalists. It's got a built-in 5 fps motor drive, digital read out in the viewfinder, removable focusing screens and a lot more. Nothing by any other brand can touch it.
The down side to buying manual focusing Canon SLRs is that no one makes lenses for it. Canon switch from the FD mount to the EF mount in the mid 80s. If you buy an AF SLR from Canon, then you'll be able to use all of your lenses on it and on the new DSLRs, too. The same goes for Pentax and Nikon.
The T-70 was my first SLR and it's a good one for a beginner. FTB is a tank of a camera and great for macro shots since it has mirror lockup feature. AE-1 Program is an iconic SLR.
The A-1 is an advanced version of the AE-1 which has the ability to accept a 5fps motor drive as opposed to a 1 fps autowider for the AE-1 cameras.