It is clearly the Yashica GSN. I'm tired of everyone saying it's this one or that one - next thing you know they're mentioning cameras that are almost impossible to find or seem to forget that we're talking about $50. Or it isn't really a true rangefinder... They'll start saying the Canon QLIII or the Konica S2 - Never seen either one of them go for less than $50 unless it was a fluke. Then someone will mention some camera that seems to exist in only an alternate universe or they'll say, "...well, it's scale focus" blah, blah, blah. No.
The GSN is plentiful. It has arguably the best lens slapped on fixed lens rangefinder. It meters to 1000, it has THE most accurate and powerful meter. I has a "smart" diamond-shaped contrasty patch. It uses batteries that are currently available. And it always costs less than $50.
There's no need for a poll. It's the GSN. It just is. Period. Anyone who suggests any other camera is simply wrong. I have spoken.