If you use unthreaded 12 gm cylinders they are neither heavy nor expensive. You can buy these in any sporting goods store or the sporting goods department of any X-mart as they are used in Paint Ball guns and come in boxes of 15 or 25 for less than $.50 each. An Innivations Superflate and others use them.

I carry a mini-pump to get the tube seating checked and inflated to 20 - 30 psi followed by a single CO2 cartridge which gives me 100 psi in a 700-23 tire and is much faster than pumping it with the mini-pump. The combination of the mini-pump, the superflate and 3 CO2 cylinders weighs less than a standard frame pump.