I agree with the OP. I purchased my own recovery/recharge machine also. It's a dual R12/R134 model. I was quoted near $500 just to change the pressure switch on the drier, the drier and for the appropriate amount of R12 to fully charge the system. That was ridiculous to me as I knew I would eventually need more a/c work and I sure wasn't going to keep paying them outrageous prices to do it.

They were charging me $50 per pound for the R12, and they were the least expensive place I could find. Well, I purchased a 20lb cyinder of Dupont R12 for 10 bucks per pound. I also purchased a new 30lb cylinder of R134 on sale for just $150. I figured it wouldn't hurt to have just in case someone else needed to use the machine.

I had absolutely no experience doing a/c work, but I've been learning as I go along. And like the OP, I also hate the scams involving R12 and the "rarity" of it which they say warrants the price. What a joke.

By the way, I've only used the machine twice so far, but the work I did myself has already saved me more than what I paid for the machine and all of the refrigerant. And that doesn't even take into consideration the convenience of doing it at my own place when I want.