I always grumble when I read threads about guys just going to the auto parts store, getting a can of R134a, and recharging their A/C systems. Here in WI, it's banned for consumer use. Only place you can get it is thru a repair shop that's licensed. And then, they can only buy it in 30# kegs.
But...The little 12 ounce cylinders that power those portable air horns are nothing more than R134a! The fitting is different on the top of the can though. So, it's illegal to add more refrigerant to your A/C system, but perfectly fine to let it blow out into the air??!? I'll never understand this state's stupid laws.
Ususally when I travel out of state, I'll stop somewhere and buy a couple cases of 12 ounce cans of R134a. They usually look at me a little funny when I'm buying such a large quantity of it, but I'll just explain that I'm from WI, and it's not available to us here. Never had a problem. One store clerk even joked that I was a modern-day bootlegger!