Not worth fixing a broken valve stem - they are about $2 for a new valve from the auto parts store. Flatten the tire (sounds like you already have), break the bead (easy enough by hand on these little suckers, change the valve, reinflate. Remove the valve core to increase air flow and make it easier to reseat the bead. Dish soap on the shoulder of the rim also helps get it to 'grab' and begin pushing the tier up the shoulder. Then put back in the valve core and reinflate to the desired pressure (less than 10 psig I recall)

Inner tubes are not necessary - just make sure the rim and tire bead is clean and smooth. Check for leaks with soapy water and address as required. Looks like two tubes will cost you $60 plus installation vs. $2 for a new valve.