Any old rangefinder will probably suffice, and, believe it or not, a fixed-lens rangefinder camera might be the best way to go. At least with such a camera you will be shooting rather than lusting over what other lenses you can buy for your camera.
Early Minolta, Canon, and Yashica fixed-lens rangefinder cameras are fully mechanical, and operate without batteries or meters. If you have been shooting manual cameras, or know how to use a hand-held meter, one of these is a good way to go.
Then there are hybrid cameras which feature manual or automatic operation, like the Canonet QL17 or the Olympus SP. These are good cameras to start with as you can use the built in meter to adjust or verify your settings, and both cameras are capable of taking superb quality pictures.
The latest of the fixed lens rangefinder cameras featured aperture-priority automatic or full automatic operation. The aperture-priority cameras are the better choice as you can still have a great amount of control. The best cameras of this type for the money are the Yashica Electros; all have outstanding lenses, and many are almost giveaway cheap. And lately their prices are appreciating a little, if you decide to move along to a Leica, you won't lose anything if you sell your Yashica.