It was available to stream free via NPR for a couple weeks, which is when fandom-in-general fell in love, but that came down when the for-pay itunes album went up. (One thing about LMM, he really understands new-media marketing.)

I missed the NPR window and listened to most of it on Spotify streaming, where it is still free, at least if you have Spotify. IDK if any other legal streaming services have it? I'm sure there are pirate dropbox versions but I can't point you to it.

And yeah, I think most of it's on youtube.