Larry,
Another board I frequent, the updated FireBoard has been spoken highly of. Not sure if that’s in the price range though.
Are you just wanting it for temping or would you use it with charcoal/stick burner? I ask because of the ability to add the fan port to the grill, and FireBoard has this. I’ve actually thought of getting this for my Weber kettle.
But, if you are wanting very simple, thermo...my trusty Chef Alarm is great! It only accepts one probe but I just use multiple probes and either tag them or remember what side is what and plug in each. It’s not WiFi/Bluetooth, so that’s the other thing. It’s just a simple thermo/alarm and has worked great for both my kettle and the 3D (I use the Chef Alarm and the built in thermo on the 3D for briskets/pork butts to monitor multiple spots).
So - what functions are you looking for and what is the price range?