Rollei 2.8C
I happen to prefer the later Rolleis that have the removable waist level finder so that a Rollei prism can be fitted allowing eye level viewing with unreversed image. The C, as I recall, does not have this feature; the E and F models do, as well as the Rollei T (I have this model) and the Rolleicord Vb, I believe. Your price for the C is probably OK. Frankly, the 3.5 Tessar on the T and the 3.5 Xenar on the Cord are perfectly fine lenses when in good condition without the very high prices of the -Flex E and F models. If you go for the prism models beware of condition of the p--they often have glass separation problems which may not be fixable. As a matter of interest, the T model Tessar was considered to be quite a good lens using rare earth glass.
Hope all this doesn't confuse you! Condition of whatever you buy is the most important thing!!