I mentioned in a comment that it's too bad John Cleese's recording of Screwtape Letters is no longer available. It turns out I was wrong. As another commenter noted, you can download it at Audible.com for $7.49.
The recording was done 20 years ago. I probably first heard it (on audio cassette) 10 years ago. Cleese's reading--or reenactment--is brilliantly entertaining (and edifying!). I'd highly recommend it.
Update: Mark Tubbs points out in a comment: "Also, it should be pointed out that you can only take advantage of the $7.49 price for the download if you sign up for at least three months at that price, billed on a monthly basis. Regular price for a single download is $10.49."