I've just discovered this post and it's very exciting. I have the original recordings off the radio, plus I have them on Vinyl (one of these was different to the radio show and CD version) and if you need it, I have the entire radio series on CD and on downloadable Flac file.
Also have books, Videos, DVD's of TV series (much better than the movie), computer game, Movie, scripts, T-shirt and have seen the play with original Radio & TV cast.
We won't discuss where I have the tattoo of the total perspective vortex, but needless to say, it's pretty scary.
If you need anything, let me know.
Douglas Adams was a genius of the first order and I remain a huge fan (just based on weight alone).
I wish you the very best of luck in your endeavours to make what deserves to be a great pin.
So long, and thanks for all the fish.