Ohio:
Of the four cameras mentioned, I'd personally opt for the Canon A-1 with the Canon FD 50mm F/1.4 lens. In excellent, near mint, or mint minus condition with a similar condition lens, you might find one a little under your price range.
Look for an original owner, high serial numbered body - later manufacture - no brassing, and in excellent working condition.
I recently purchased a separate body and lens for less than $175.00 and even after shooting several rolls of color print film, which turned out to be very excellent, I decided to give the body a CLA (Cleaning, Lubrication, and Adjustment) by an authorized Canon A-1 repair facility to insure its working for many years into the future - Canon will provide you with a list upon request.
Although the Pentax K 1000 is a fairly good choice, it might be difficult to find an wide array of good Pentax lenses. Before I gave my Pentax K2 to my daughter, I was able to obtain a wide range of Pentax lenses from 28mm to 200mm, but never could find a moderately priced Pentax 35mm F/2.0 or a Pentax 85mm F/1.8 lens at a good price - the later lens rarely popped up on
Ebay.
I believe that the AE-1 would be a good choice as well, but the Canon A-1 is a later model and has some additional features that make it more worthwhile.
I think that you'll find a very nice array of Canon FD lenses and accessories at good prices on
Ebay to add to your photographic collection. Again, look for items that have been well taken care of by their owners and are in excellent to near mint condition.
As for the Nikon FE suggested by someone, I am not familiar with that particular model, but I have never been impressed with Nikon cameras and/or lenses. I had to work with them for a number of years while serving as a staff photographer at the University of Illinois - College of Medicine - Peoria (Illinois) Campus and wasn't ever impressed with their quality - the 100mm Macro Nikkor lens had so much curvature of field wide open that you had to stop down more than a few stops to eliminate it and even then, its performance never match the 100mm Leica Macro R lens; always thought that they were a little over promoted/rated. But then I have also been a Leica (rangefinder, projector, enlarger) user for decades as well.
Since the SLR's you mentioned are digital, you might check out the resources and/or articles that I have listed below. It might aid you in making a more intelligent decision.
I don't think that "film" cameras are entirely dead, but I do believe that digital cameras do appear to be the wave of the future - just as 35mm cameras once were in the age of the Speed Graphics (4 X 5 cameras preferred by the press). On the other hand, digital cameras haven't yet reached their pinnacle as yet.
At any rate, here are some sites/articles worth exploring.
This site is an excellent resource of Canon FD lenses, cameras, and some accessories.
http://www.mir.com.my/rb/photography/companies/canon/fdresources/fdlenses/
This is an interesting and worthwhile article on digital lenses.
http://www.imx.nl/photosite/comments/c011.html
Another interesting article:
Death of photography or why the concept of 'digital photography' is doomed to die soon (November 8, 2003)
http://www.imx.nl/photosite/comments/c003.html
Some "Technical Notes" of interest, probably more technical information than you might wish to deal with now, but at least you'll have a reference point when you may be in need of it.
http://www.imx.nl/photosite/technical/indextech.html
Finally, for reviews of cameras (film & digital) and other photographic equipment, you might check out this site as well. It also might be very useful in making your decision.
http://photosig.pcphotoreview.com/defaultcrx.aspx
Well, I do hope that this is more than useful for your beginning photographic endeavors.
Bill