Archive Dot Org has a great assortment of X-1 episodes which you can listen to online, or download for your own collection. The show was one of the better presentations of science fiction radio plays, built from stories that appeared in Galaxy magazine, written by some of the best authors of the era. This program has been in the public domain for quite a while now, which kind of surprises me, as I would have thought they would want to hold on to it. Here are a few episodes to get you started; there are quite a few more available.