There are also different categories of rangefinder. The Leica is the best known of the professional or extremely high quality rangefinder cameras but back in the 60s and 70s most camera companies had decent fixed lens rangefinders available. I have a Yashica Electro 35 G that I love. It is certainly in a whole different ballpark than a Leica or Contax, but I got it for about $20 and it is reasonably small and very easy to use. Actually, it is kind of big, but there are no accessories and lenses to worry about. Canon Canonets are more sought after, but still commonly sold for reasonable prices.

Here is a nice site that emphasizes rangefinders: http://www.photoethnography.com/. Forgive them the evil window resize script, they know not what they do!