Contrary to what some think, having a 609 certification WILL NOT guarantee that you can buy R-12 in just any area of the U. S.
Some states and municipalities have additional restrictions. In these cases, you more or less have to be employed in the field and must be able to prove it.
No point in going after one if it's not going to fly in your area. If it does and you believe R-12 is superior to R-134a for systems that were designed for R-12, go for it.