The Contax I is notoriously unreliable and difficult to get repaired since it has a complicated and unusual shutter. There were also many variations over its production period with substantial changes in its shutter mechanism (no speeds slower than 1/25 in early versions) and rangefinder. I own a working example, and while it is an interesting camera to work with it is also something of an ergonomic disaster. You will notice the nobody else ever copied the front winding knob, and for very good reason. I don't have particularly fat fingers but have a hard time winding the camera even with a collapsible 50 mm Tessar mounted and extended to shooting position. With an 85 f/2 Sonnar or 35 mm Biogon it is much worse. As for prices, they seem to vary on eBay from $300+ for non working examples to much higher than that, and sellers are rarely inclined to offer any kind of guarantee, which seems reasonable to me under the circumstances, since the shutter blinds are moved by silk ribbons that can fail at any time due to age and wear. But if you want to experience early 1930's tech and some excellent lenses (Sonnars, Tessars and Biogons can be surprisingly good for their age) then give it a try.
