Used corny kegs came from the soda industry, but stocks seem to be drying up pretty quickly. Prices have gone up from $20 per reconditioned keg about 4 years ago to around $50 today (some are asking that just for used kegs.) Outlets that I've previously used don't have any kegs, altough I've managed to find one reseller offering a resonable price. What happens when the supply dries up completely? What's the future in kegging with cornies?

EDIT: I'm looking for tangable, factual answers rather than opinions - alternative systems, estimates of how many used kegs are still to be released and other facts to support investing in a keg system now.