We haven't needed to use our R-1234f machine yet, which cost $11,000, and it needed to have 10 lbs of refrigerant put in to set it up and get it ready for when the time comes. A 10 lb cylinder wasn't $1,000 (our cost) but it was over $800. You sure don't want to do something wrong and lose any of it to the atmosphere! IIRC, R134a in a 30lb cylinder comes to around $8 a pound, give or take a little. We guard our remaining supply of R12 with laser guns, lol. Rarely, and I mean VERY rarely do we work on anything old enough to have R12 or that hasn't been converted to R134a years ago already so, the 30 lb cylinder plus what's in the recovery machine we have yet will probably last forever.
For the cost of R12, if one of those systems needs to be opened for repair, or it leaked out, you may as well convert to R134a. Depending on the vehicle and system, the cost comes out a wash.
The sale of 12 oz cans of R12 is illegal in Wisconsin. I wish they'd make the sale of those "A/C Pro" type products illagal too. They all have sealer in them and the sealer works really good. Seals the leaks, even the ones you want like the orifice tube or expansion valve, gums up the desiccant in the dryer, etc. and just makes a general mess of the system. Then again, I suppose you could call it job security for the professional auto techs
