I bought a Seek that uses my IPhone display probably seven or maybe a little more years ago. Bought it to locate the tubes in my hydronically heated floor to help place my two post lift.
Worked great for that. Also surveyed the house and shop for thermal leaks, although I don’t know that I found any surprises.
I also can see where the electric lines run, but since almost the entire shop is surface mount emt, that feature isn’t terribly useful..
I doubt if I have used it since the novelty wore off, although I should check out my pump house at the shop.
I have no idea where it is now, though.
I would look at the cheapest Chinese import you can find with decent specs. This is a pretty good example of a one time use tool, unless you’re into this kind of thing.
Absolute numbers aren’t of much use for most people. You’re looking for gradients and hot spots, something most any inexpensive generic imager will do.