R-12 refrigerant - $14.99 a can
Another member recently posted here that he found R-12 in his area for $14.99 a can at Auto Zone.
I called about half a dozen Auto Zones in my area and sure enough, it's $14.99 a can, unfortunately they are all out of it and many report they have no idea when it will be available.
If you have a 609 certification and plan on sticking with R-12(I am), call all of the Auto Zones in your area and see if it's available. In my area it sells for $26 a can and up. $14.99 is a bargain.