They are disappearing because people are buying them. The range of SQ's and lenses has decreased considerably from two years ago on Ebay, and it is the same with Hasselblad, etc. Photographers want to use film again. But the Bronica SQ in particular has been getting great press on the camera forums, justifiably so, and rather than being seen as a wannabe Hassel alternative is viewed in a more considered light for what it is.