The current price is a about $30 per can if you buy in cases of 12 cans.

http://www.r-12.com/?_kk=r-12&_kt=c2b99675-319f-4c77-98ad-fe53930c3a3e

I think I have an unopened can of virgin R-12. The can might have some surface corrosion but the content should be fine. If interested, please let me know so I can dig through the stuffs to find it.

OP must have reasons not to use R-12. IMHO, if you have a R-12 system and it is a little low, the best option is to add some R-12.