The one you got is also cheap.
After you mentioned radio range and interference, I checked my thermometer. The range is crazy good. With the senders inside two freezers, both senders transmitted 50 feet through the steel walls of each freezer, 3 internal walls and one external wall. I'm using two Duracell Industrial AA's which probably helps a bit but also shouldn't run out quickly.
The Japlish instructions are incomprehensible but I think the unit is clever enough to account for freezer door opening when deciding to trip the alarm and it waits 10 minutes (or something which looks like that in Japanese) before using the temp value to indicate up or down trend.
Best thing I've bought all year.
It even has four decent neodymium mounting magnets which saves me supergluing a proper magnet on the back of the display which I had to do with my old probe thermometer and also any digital timers.