I checked around with my local suppliers this morning. It's been awhile. Most no longer carry R-12 and the one who does gets $31.50 for a 12 oz. can that has to be ordered.
The local parts people I've spoken with indicated there's just not much demand for it anymore.
I found another site on the WEB ->
http://www.refrigerantsales.com
12 can case for $250.00 - includes delivery - takes about 3-5 days. That comes out to $20.83 a can. They have an 800 # and claim to sell new Dupont R-12. Who knows?