I have 2 kinds:
a meat probe thermometer that you get at walmart in the kitchen utensil isle for $14. the brand is Acu rite. Does not seem as accurate (lol)... but it has an alarm if it reaches a set temp. I like that in case theres a spike and I can attend to it fast.
I also have a thermometer/humidifier combo. From walmart located in the hardware light bulb area with the rain gauges. I like it more than my probe one for temp. reading. It cost $7. The brand is Springfield Precise Temp. It seems much more accurate as it does decimals for the temp. Ex: 99.5. The humidity records the lowest and he highest so you can see how much if fluctuates.
Hope this helps
Steff, I went to a pet store and bought a terrarium thermometer/hygrometer for reptiles. it seems to be working pretty well, but had to be adjusted because the thing that registers the temps (not digital, obviously) are on a piece of plastic that slips inside the base that has the numbers on it. I think that's why my last hatch went south, because it wasn't reading right, and I didn't realize it until the end. I'm not sure what it's called, but I could take a picture next time I lift the lid to add water. I find keeping the humidity up is the real problem here in Utah. I imagine it's the same in your area, unless you live way closer to the lake then my sister did in Stansbury.
I have a thermometer/hygrometer in one, it's not digital but works well, it's for indoor/outdoor use and I got it at my local feed store the brand is Taylor...It seems to work and I just had my first hatch ever with one babie so far, just waiting for the others...I know alot of other people use the Accurite digital thermometer/hygrometer you can get it at Walmart.