Look at the 15-25 dollar 12 volt models. Or spend more and get the jump start/air compressor combo. It's portable, will prove its worth again and again in odd situations, and you'll love it. Fits in the tool box or under the bench or in the back of the car.

If it's a tire/ball/knicknack inflator you want, that's how I'd suggest you go.

I'd also suggest a 2 gallon+ portable air tank, because the 12v inflators aren't exactly speed demons. If you're very low or the bead is coming off, there's no hope from a 12V model; but a limited budget can afford both.

As for the jump starting, I know you didn't ask but I have 2, had 1 before, and all have saved the bacon of a lot of people, especially the ones who nose their car into a tough spot and then can't get it started--and no one can get near enough for jumpers to reach--so starting would otherwise involve pushing the car into the street or worse. A quality combo compressor/starter would pay itself off smartly in your described use.

Ben