R12 is available all the time on Ebay..$25-$30 per pound.
I bought a 15 lb. "keg" for ~ $8/lb.
I missed this by napping.. less than $3/lb.
http://www.peachparts.com/shopforum/showthread.php?t=182232&highlight=R12 post #5
You may not find these deals
, but it's out there all day, everyday.
Most major refrigerant suppliers have 30 lb. tanks in stock.
Ebay and some auto parts stores have the little cans as well. You do need a 608 or 609 cert., though. $25 online test gets you the cert. for life.