DBPOWER 12V Tire Inflator, $21 with code NQV84J8Y

When your tires get low, you’ve got two choices. You could scrounge together some quarters, drive to a gas station, fumble around with the filthy air hose, and run out of time after filling three tires. Or, you could just buy a compressor to keep in your trunk, and top off your tires whenever you want, for free. This one’s only $21 today, and even includes a warning light if you have to use it on the side of the highway.