How the hell do I obtain a rabies vaccine?

I am very involved in the lives of feral cats. I am a caretaker of four feral colonies, and I participate in trap/neuter/return. These activities do not require me to be vaccinated, but recently, I have started to assist in the spay/neuter clinics for feral cats.

Because I’m handling feral cats, I need to have a rabies vaccine, and it has been impossible to acquire. Everyone else at the clinics got them because they’re a vet or a vet tech or got the vaccination years ago.

I have called my Student Health Center, and they thought I was crazy and failed to comprehend why I needed the vaccine. (Even if they did comprehend, they clearly don’t have the vaccine and basically said they were unable to get it.) I don’t really have a primary care physician because I just get a yearly check-up with my gynecologist, and my gynecologist’s office is not really in the business of obtaining rabies vaccines.

There is a national shortage of the rabies vaccine, and it is extremely expensive. I cannot figure out how to get it. Does anyone have any knowledge of this?