For whatever it's worth, my wife got me a Thermapen for Christmas 4 or 5 years ago and it's easily my most favorite kitchen/grill gadget. I wholeheartedly agree that $100 is really steep (I think she got mine on sale for $80, but still)... but honestly every time I use it I still think it's worth it. It's been one of the key things that has allowed me to up my grilling game significantly I think. In fact, for Christmas Eve dinner, a last minute health situation meant we had to host, and my mother in law wanted us to use a beef tenderloin she had. I cut them into 1 3/4" thick filets and reverse seared them on the Genesis and they came out absolutely perfect (slowly brought them to around 115 then cranked the heat and did a quick sear to about 125-130). I think they were the best thing I've ever cooked, and there were lots of compliments. I don't think there's any chance those could have been cooked so perfectly without a good instant-read thermometer.
At the time I don't think any of these clones being discussed here were available or I'm sure we would have tried one. We had tried quite a few other digital cooking thermometers, but those took seemingly FOREVER to settle in on a reading (not a good thing when working on a hot grill). After seeing endless endorsements from Alton Brown and America's Test Kitchen and such and watching them use them on the show (and seeing how fast they work) we finally broke down and got one. I think those endorsements are why they keep their high price. I'm sure the lower-cost models being discussed here would be sufficient for the home cook these days though.
FYI, the big difference with the Thermapen compared to the cheapies that came before it is the Thermapen uses a thermocouple for measuring temperature versus a thermistor which is used in lower-cost models. Thermocouples are much faster (apparently). The Thermopros also seem to use a thermocouple as well. (Incidentally, the ThermoPop from Thermoworks, which we've gifted a few times, is a thermistor design hence why it is a little slower - though Thermoworks has done some sort of magic to those as well as they're still much faster than the cheap models you'll find in your grocery store).
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) I would go for an MK4. But since I am not, this TP-19H seems like a pretty compelling alternative for a fraction of the price. No, it is not the same quality, but the gap is really narrowing as I think you can see above. I would love to but can't have a Lexus or Audi; I don't want to drive a refurbished Yugo. I am quite OK, though, with a Honda or one of the better new Chevrolets. I think this thermometer makes sense for someone in my position but completely see why someone in a different one would go for a Thermapen.
