Before you try to put R134 into your system, I think you better do some more research on your system. The 850 uses R134A, *NOT* R134. R134A is more expensive, less efficient, but safer for the environment. In fact, R134 is becoming increasingly harder to find. Most places that supply refrigerant no longer stock R134, instead, they stock R134 to R134A conversion kits.

And yes, R134A can be purchased at many auto supply shops. I got a kit for a friend from a refrigerant company that specializes in refrigerating systems for biomedical research.

Try UAP. I'm pretty sure they'll either have it, or know who to ask for it.