You're not paying for the accuracy so much as the speed and reliability. The packaging matters a lot. A $10 knife and a $100 knife are fundamentally both just chunks of metal, but they definitely don't perform the same way. It's much, much better than a $10 thermometer.

There's a $30 Thermapen (the Thermopop), for what it's worth; it reads in 3 seconds, versus low hundred milliseconds.