So there was a free weekend for this game on Steam, and I had a lot of fun, especially the last mission I played mere minutes before the free weekend ended, and I'd love to be able to listen to the music outside the game.
There are youtube recordings, but they're a bit awkward, with fade-in and low volume.

I took matters into my own hands and used a site to convert youtube videos into mp3s.
After volume adjustment and tagging, I produced a .rar that'll have to do until someone who knows how to rip music properly does the soundtrack justice:
http://www.mediafire.com/file/uklir887w2uvv84/Helldivers_OST_%28YouTube_recording%29.rar