Radio shows: Internet Serendipity in action

Last week I was cleaning out my closet and came across some old radio shows on cassette that I had purchased way back when. I've always loved the old-timey serials they used to play; especially the old The Shadow shows, and The Spider. I decided at some point I needed to start hunting them down in digital format.

So, imagine my surprise when this
Sherlock Holmes Radio Shows archive showed up on del.icio.us most popular sites! There's a ton of awesome mp3s on here! Including Sherlock Holmes vs. Dracula!

Anyone know where I can download other ones from? I'm willing to pay a reasonable price for these...and I actually own the old Shadow shows on cassette, besides which, I'm not sure a lot of these aren't already public-domain.