Okay, I think you'd need to buy the following:
heat alarm, $25.44. That'll get the alarm beeping if the temperature increases in your garage by 8-degrees per minute and starts beeping at 45 degrees or something.
Then you'll need the
Ring Alarm with base station, $269 (or on sale at
Best Buy online right now for $239). That gives you a motion sensor and door sensor, keypad and the base station to which everything connects. If you want to set up a home alarm, now would be the time and you should get a bigger set with more sensors like
this one.
Finally, you'll need the
Ring Alarm Smoke & CO Listener, $49.
You don't need to pay a monthly monitoring fee for any of this. Starting from scratch you're looking at ~$325 to make this happen.
Maybe there's a cheaper way to do this, but since I'm in the Ring ecosystem already, it wasn't expensive to add this protection.
If you're curious about the Ring Alarm, check out my jibber jabbering about it
here. It is amazing, cheap, and you can install it all yourself very easily and with no skill in a couple of hours. I have freeze/flood sensors, window sensors, door sensors, motions sensors, cameras, etc. It's sick. I just put an indoor motion activated camera inside my garage, too.
If someone goes in there to steal my stuff, I want to see their face so I know who to murder.