I bought a $3 Nikon FM at KEH out of the as-is bin... I tore it apart and immediately put it back together, and I had a $100 camera... I sold it at a yard sale, as I already had an FM, but it was the best $3 I ever spent on the Internet. I'm going to purchase a bad foam Minolta today, to go with a 45mm lens I have.
If you buy a "working" camera from KEH, go with the bargain grade, as the cameras are still fully functional and only have a few "battle scars" on them. Expect to give it a good cleaning after you get it, as I've found "bargain" cameras are sometimes a "bargain" only because they are dirtier than an "excellent" camera.
I'd go with the F3hp if you wear glasses, but even without my glasses on, I prefer the F3hp to my mother's FE2 or my FM, as the viewfinder in the "amateur" cameras is hard to see all at once, especially with the information scattered around the frame, as opposed to all of the info at the top of the F3 finder. Also, the motor drive is better/faster/stronger, and the waistlevel finder is useful on the F3.