Best used 35mm SLR AF Camera?

I'm looking to buy a used camera off Ebay. I'm unsure of what I should get. I have a Canon AE-1 and I love it, but I'm looking to get a more modern camera. Since they no longer make new film cameras I have to buy a used one. I'm not picky on which of the brands Nikon or Canon. I would like it to be a good camera that is auto-focus. I have spent some time looking and am getting overwhelmed with the options. I do not know the differences between all the models such as Canon's rebels and elans. I'm just looking for a little help as to what to look for and what is a great all around camera that will not break the bank. Most of the ones I have seen are 50 bucks or less, but even in that price range there are a few dozen different models. Any help with what to look for and the differences between the different models would be appreciated.

Avoid the old obsolete 35 mm SLR cameras like the AE-1. For about the same price, you can buy a Canon EOS or Nikon 35 mm SLR with standard lens (under $150) By purchasing 35 mm cameras that are under 20 years old, you can use the same lenses on just about any matching dSLR you may later buy

NOTE: It is usually NOT recommended that you buy any camera gear unless you can first test it. That means you will need to look on craigslist in a city near you or at a local camera store. Unfortunately, eBay has become a dumping ground for damaged cameras

I would suggest Canon Elan 7N, it has auto-focus, 4fps, Ef lens mount so all canon lens work.

How old is the Pentax SFX? They do sell cheap and they offer autofocus which reviewers say is actually quieter than that on many modern dSLRs. I think they take KA-F lenses plus earlier non-AF K mounts. I seem to remember that they can be set to actually shoot automatically when something comes into focus - that is with non-AF lenses only but what a facility! It's years since I used one but I do remember being very impressed.