Watch this test of several portable tire pumps. The best three, in order, were: Husky (Home Depot) Campbell Hausfeld (Menards) Pittsburgh (Harbor Freight)
Suggestion: carry a spray can of ether and a lighter in case your tire is unseated from the rim. Jack up the car, spray some ether inside the tire (as in, where the tire is unseated) then light it for a loud pop and the tire bead coming out to meet the rim again. Tire shops use an air cannon for this.