Why do I buy any of the stuff I have? Plus I have a car that uses R12

The local parts store I use still has small cans of R12. I have the certification to buy it but we don't service too many r12 cars anymore. Last car I charged with R12 was a 1970ish Cadillac with a charge weight of close to 3lbs and I remember the 12oz cans being in the range of $50 at the customers cost.