Don't forget the thrift/opshop/charity stores. I've got most of my rangefinders from there and the best thing is you can see they have come straight from the original owners and have not been "hacked" with as some of my evilbay specimens have been. Oly RC $20, Yashica CC $10, Canon GIIIQL17 $10, Yashica Lynx 14 $10 - all working perfect.
On the Oly side, there is also the EC and the DC, both electro types though and no manual controls. Nice though.
These rangefinders have a charm and seductive appeal of their own thats hard to explain (gulp).
An OM-1, I concede is often the more practical choice. But then more so is the Canon G9, and then to my Nokia with a Zeiss in it.
There's something else involved but I'm not sure what it is.