$40 for a can of Freon? I think /not/.

I'm not sure I'm too concerned about all the hand wringing behind flammable refrigerants

Any of the traditional freon based stuff (R-12, 22, 502, etc) become UNBELIEVABLY poisonous (phosgene) if run through a flame, so if you are "somewhere" that there is a fire, and trapped, you are screwed, anyhow, and if a refrigerant line breaks near a fire/ ignition source, the OIL in the refrigerant will cause one hell of a fire, to boot.

Your car already has fuel, oil, brake fluid, that will burn, along with pounds and pounds of plastic which becomes VERY toxic when burned

So 12 oz or so of propane doesn't sound all that dangerous to me.

The PROBLEM as I see it with some of these off brand concoctions is that many are backyard stews of ??? and you may not know WHAT TF you are getting, really.