Besides a LHBS, at what kinds of stores can you find the co2 cartridges for a keg charger? Would someone like Fred Meyer have them? (kinda like a walmart for those who aren't in the PNW).
Restaurant supply stores and mom and pop hardware stores sometimes carry them. Be sure to get the food grade ones. Some people use the ones for air guns but they can have an odor from the fill lines in them.