I was interested in this sensor so I contacted GSS which relayed my request to their North American partner, AirTest Technologies. I was very impressed with the quick response time and they promptly provided me with information on their products.
For my purposes, the Corzir-A (Ambient) with a range of 0-2000 ppm is perfect. It also has optional temperature and humidity sensors. The part number for that combination is COZIR-A-2000-X-H and I'm told it's $183.
How does that compare to other CO2 sensors? It's definitely more than I was hoping to spend, but at the same time it may be worth the price if it simplifies my project.