You can also get what is called "Freeze 12", which is a blend that is fully compatible with R-12 systems. It costs about $ 1 more than R134a per pound. Oil, pressures, etc are very close to R-12 and can be dropped right into an R-12 system. Only hassle is you need to add conversion adapters for the charging ports. It has it's own unique thread to meet the EPA SNAP requirements.
As for R-22, it's still cheap and I think will stay that way for quite a while with the final end of production not until 2030.
paul
As for R-22, it's still cheap and I think will stay that way for quite a while with the final end of production not until 2030.
paul