You need a license to buy R12, even from ebay.

My 1991 300se has envirosafe es12 in it, installed by the previous owner, and it seems to work well. Not as good as r12 but better than r134. I had r152 from canned air in my 1979 300d, it worked well too except when sitting in traffic for long periods of time.

__________________
"It's what non-car people don't get. They see all cars as just ton-and-a-half, two tons of wires, glass, metal and rubber. That's all they see. People like you or I know, we have an unshakable belief that cars are living entities..... You can develop a relationship with a car, and that’s just what non-car people don't get."
-Jeremy Clarkson