Okay, so a few weeks ago I paid actual money to download an audiobook of Polidori's The Vampyre. It was worth it to listen to someone read the piece out loud, because the narrator, B.J. Harrison, emphasized things that I wouldn't have, and the pace was different for me. He does put on an affected accent which I do not believe is necessary, but it is a vampire story. It was worth two bucks.
However, if you are too cheap to spring for a semi-professional read, by all means dig into this presentation from HorrorAddicts.net - or as Host/Sad Girl Emerian Rich likes to call it, Horror Addicks. Once you get past all the ads and banter about exciting, eventually-to-be-written fanfiction, you will be treated to an auditory experience like no other.