The collectors recognize a lot of variations within the Contax I production, the later ones may have no problems as shooters, the collectors have inflated prices, they were real cheap at one time.
A parts Kiev can be got real cheap and if you need to fix a Contax II, the Kiev shutter module is nearly a straight drop in, saves a lotts money as stripping the crate can be difficult, and parts impossible, it is not that Contax II are expensive, to make counterfeiting worthwhile.
The Contax II and III are real nice cameras for shooters and real cheap, early Kiev's arnt a lot different in price or utility, either can be very reliable as shooters but are slow handling.
The J12 (35mm) and Orion (28mm) can need fettling before they mount on a Kiev or Contax II but are nice performers, the Orions are distressingly rare.
The Kiev and Contax II concentric cassettes are interchangeable. the Kiev ones are real cheap.
Some of the Kievs are being scrapped to make Contax and (Nikon) lens to M body adapters, so Kiev parts are readily available, except for the lens panel.