It is not illegal to buy or sell R-12, they merely stopped producing it. You must be licensed to recover, charge, or otherwise handle it. Prices have fallen steeply in recent years.
Edit:
My intention was to point out that R-12 can still be purchased and sold, by licensed individuals or by company representatives that provide proof of a licensed employee. There is also provisions for wholesalers who merely retail but not use the product.
R-134A requires no licensing to purchase or use as is evident by the rows of product for sale in retail locations. Try it, Walmart is not going to ask for your 608 or 609 license.