I bought a Topdon TC001 a year ago that in my experience is significantly more responsive and higher resolution than similarly priced FLIR or other name brand options at that price point. It appears there are even more low cost options now.
I find it rather interesting that companies like FLIR are limited by regulation (I believe US export bans) from selling IR cameras with greater than 9fps. there is also a resolution cap but I forget what it is off-hand. Strangely enough this doesn't stop US citizens from purchasing higher performing cameras from non-US companies. I think technology has come down significantly in price over the last few years and you can now get smartphone attached versions like infiray for a few hundred bucks.