What's wrong with a temp gun? $25; problem solved. They're accurate to within =/+ 1 degree?
I haven't had a thermostat/hygrometer in my facility or in my bins in years. If you have a thermostat and a steady ambient room temperature, you know spot on what your temps are thereby eliminating completely the need for a digital thermometer/hygrometer.

Though I haven't shopped for one in many many years, I would imagine (like every other retail item in the world)that a price bracket or two up that you would find a slew of digital thermometer/hygrometer combos that are infinitely more accurate. Or use two, or three or four and you can find the mean temperature and humidity without a malfunction/guessing game with a single one.
Tape an old fashioned glass thermometer (like the one mommy used to use when you felt poopy) to each side of the tank. $20; accurate. Problem solved again.