Why in the world are thermal imagers so expensive?

I don't know much about thermal imagers but i did some look and this is what I found: http://en.wikipedia.org/wiki/Thermography "Thermal imaging cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often export-restricted due to the military uses for this technology. Older bolometers or more sensitive models such as InSb require cryogenic cooling, usually by a miniature Stirling cycle refrigerator or liquid nitrogen." I hope this helps.