As always with threads like these, everyone will simply suggest what they own. Let me add my own experiences:
A Minolta 7s can be had for less than 50$. It's a solid rangefinder with a sharp f1.8 lens and permits fully manual operation (vital if you want to know your stuff). The rangefinder is much brighter than the Petri 7s, take that into account if you have a choice. In my opinion, the 7s is vastly underrated. Most people look down on it because they want the slightly better and much smaller 7sII, but don't let that misguide you. It's an excellent performer.