There was a book put out by Robert Parrish in 1974, and the book outlined some of Vincent's Radio career. I'm not sure if you are looking to find out this or just what is available on cassette. I have been working on a list for about 5 years now and every now and then I find out there is something new that I had'nt known about.
There also is a site called "the sound of vincent price" but I find it isnt the best source of info for VP audio and the webmaster doesnt respond to my emails. Maybe you can have better luck.
You may want to try amazon for any cassettes or Cd's but i would recommend trading online or perhaps using Ebay to find out of print material. Below are a few links to get you started on collecting. If you need any more help you can reach me @ the vincent price club.