I just bought a DSI III with adjustable tec cooling from a guy on cloudynights. For more information see this thread here.
http://www.cloudynights.com/ubbthrea.../o/all/fpart/1
I think it is good value for money especially with the added tec cooling. It has the same sony chip as the QHY2 and costs half the price. This is my first camera so i think it will be a while before i learn how to take decent images, but theres some good info on tec cooling on that link i posted. If your handy with electronics it will make a noticeable difference.