OM-10/20 and probably the 30 and 40 too, these cameras are super common, especially the first two and very damn cheap. I usually get them for 20-30 dollar with the 50 1.8 MIJ and sometimes even databacks and whatnot. They're good working horses, image quality (of course) on par with the OM-1/2/3/4, OM-20 has aperture priority AE and full manual controls, whilst the OM-10 needs the manual adapter for the latter. Real bargain!