The plain Voigtlander Bessa cameras can also be a very cheap alternative to the Bessa I or II (which are very pricey). If you are patient, you can find very late, post-war Bessa 6x9's with coated lenses (vaskar or color-skopar). The Bessas are very abundant, and often go overlooked compared to the Bessa I and II. Just make sure you get one with a good lens and in good shape. I picked up one with the excellent 105/3.5 color-skopar recently for under $30.The other advantage is that it came in a compur rapid shutter, which I prefer over the prontor in my Bessa I, since the compur goes to higher speeds (1/400 vs 1/200).
I also like the Perkeo cameras (6x6) very much. I prefer the ones with color-skopar lenses, but I've heard the vaskar is good also. The Perkeo I can be a good deal for arouind $50, Perkeo II and Perkeo E cameras are getting to be very expensive. The camera's best attribute is that it's tiny, not much bigger than a 35mm folder. A Bessa 66 with a late coated lens might also be a cheaper alternative.
I usually carry 3 of these backpacking: a perkeo (6x6), and 2 bessas, one with an insert so I can shoot 6x9 as well as 6x4.5! The 3 cameras are lighter than my Mamiya TLR, which I used to carry, but was just too heavy ,and took too long to unpack. I can keep a folder in a pocket to take pictures without havign to fully unpack.