I became interested in such a tool when I was involved with DIY jobs in the home. The price range is what killed my interest. At the high end, the cost is $25,000. That's around half what my basic set of carpentry, electrician, and plumbing tools runs.
FLIR sells a lot of different imagers, Fluke has a professional line of imagers (some are out of stock), and big tool makers like Ridgid (RT-9x) are also in the business. I would try to find some youtube videos with hands-on demos of products finding hot water lines underneath concrete flooring or inside cement tile, stucco, ceramic, marble, sheetrock and wooden walls. When you find a decent imager, report back here. What works for a pro should work great for an amateur like me.