For some reason, Wally was carrying the little Campbell-Hausfeld 12VDC compressor for less than $10 for a number of years, but now they are more like $30. I keep mine in my truck and have used it to inflate truck tires (My own and people I have helped) and trailer tires.
Has a max pressure of 200 or 250 psi and takes a loooong time to fill something like a repaired tire, but lots easier than changing tires. It has a very convenient setup on the tire end that allows me to put my trusted pressure gauge on a fitting while the compressor is pumping, so I can monitor the fill. Also has on/off switch on pump so I don't have to unplug it to move to the next tire.
I also carry a tire plug kit so I can repair nail holes and stuf like that without removing tire from truck; sometimes I don't even need to jack up if the puncture is visible. All very handy, esp when in the boondocks of Utah on a Sunday...
Hmm, just searched and can't find the one that plugs into cigarette lighter, just the cordless ones (I don't know if internal battery
would run long enough to inflate a tire and it probably uses 120VAC to recharge, so there may have to be an inverter involved for roadside use.
Amazon has the cordless one for $16.17