Case closed. Turns out it was "Thirst" (1979). Very interesting twist for a vampire movie. It ends very ambiguously, in my opinion - but I'd still recommend it. Thanks a lot for helping me figure it out.

I found a great video store in Portland, Oregon that has the most obscure movies you could think of. It also has a lot of interesting props from movies in display cases, such as the knife used in the original "Psycho" and the severed ear from "Blue Velvet".