Statistically cars converted to 134, even a thorough conversion only last 2 years before serious attention is again required.

The cars requiring R12 are now quite old and hitting the wrecking yards or the crushers in record numbers. This has decreased the demand for R12 which of course has decreased the price. It is now available at prices not much higher than 134.

I have seen people spend literally $1,000 to convert to 134 so that they can save $50 or $60 on refrigerant. I guess I'm old enough that the math I learned was different from what has been taught in later years.

Stay with R12. Leave the 134 and worse yet, the junk refrigerant conversions alone.