Are they worth it? That's for you to decide. 90 to 100 bucks is a ton for just a thermometer.
Unless its a red one and then its worth every penny.
I got mine as a gift, rarely cook without it. Even use it to check the temp of my beer.
Pete-my first UDS,a brick pizza WFO, a leaky Chargriller offest, wifes Weber Genesis gasser,a Lightening Fast RED Thermapen, baby Traeger, One-touch copper Kettle