Frogg,
I own SWIR cameras and will likely be rehousing one of them as they are specialist in their applications. I have found that I have little use for what SWIR offers in terms of imaging. Common uses for SWIR are silicon wafer and solar cell inspection, art forensics, food inspection on production lines and SWIR laser beam shape analysis beyond 1.1um. The SWIR camera can image through glass and other materials that offer transmission in the band. Common plate Glass offers decent transmission up to around 2um. This is why standard optical glass lenses do work on SWIR cameras but the glass does limit performance above 2um. There are SWIR rated lenses that offer the full band coverage but they cost a lot more than common optical glass lenses. I have no need of any of these applications.
MWIR and LWIR cameras are far more useful over a wide range of applications. SWIR cameras are intended for more exotic applications so tend to be produced in smaller numbers and so retail at higher prices.
My FLIR SC4000 cooled InSb Science Camera is capable of imaging in both the SWIR and MWIR bands and was specifically selected for a specialist application prior to my ownership. It imaged bare helical nichrome or tungsten heating elements that were located behind 6mm thick high temperature glass and ceramic plates. It identified any areas of the bare heating element that was suffering overheating due to the physical design of its ceramic holder. The SWIR and MWIR capabilities of the cooled InSb wideband camera were essential for this R&D task. A very specialist application however ! Having that specialist imaging capability cost the company over $100K
As previously stated, when looking to buy a SWIR camera, the cost of a suitable lens needs to also be considered as generic unfiltered optical glass lenses are only useful over part of the SWIR band. Many modern optical glass lenses also have built in filtration that can reduce performance in the SWIR band. Old CCTV lenses are often the preferred option if operating on a tight budget. The Lens also needs to be specified for full illumination of the sensor array. A SWIR band C mount lens is not a cheap item to purchase new and rare on the used market. Many used SWIR cameras come with either no lens fitted or a conventional optical glass CCTV lens as they were often used below 2.0um.
Fraser