IR point thermometers have come down a lot in price. IR imaging cameras haven't.

Is there a reasonable approach to using the point thermometer to determine how well or poorly insulated my walls currently are, or should I spring for a "proper" evaluation? (Or try to get an imager at tolerable price through eBay?)

Yes, I know some folks have kluged frameworks with stepper motors to scan and area and build up an image out of individual points. If it came to that, I'd rather throw money at the problem.

(The last few times I had energy audits done, they said they'd check on this... and then didn't do so. Admittedly, having had the place air-sealed and the roof insulation deepened I'm already ahead of most of my neighbors, but I'm still willing to invest in improving it further if there's clear evidence that doing so would help.)