I've heard the soundtrack is great, but just to be clear, we don't get a copy of the soundtrack if we buy it, right?

It's included in the game files after installation.

http://www.gog.com/forum/general/release_the_last_federation/post38

The soundtrack was commissioned to an independent artist, who has worked closely with the company. I don't know the shape of their agreements, but it's likely that he retains the right to control distribution of the soundtrack outside the game. As Immoli says, the game comes with a soundtrack in OGG format. If you would like other formats, you can buy it from the artist at http://arcenmusic.bandcamp.com/album/the-last-federation

It's five bucks, and well worth it, IMO.

It certainly sounds good to me, and VLC reports 256kbps on the three tracks I've examined. Most of my music collection I've ripped at 192kbps MP3's, and I don't have the "golden ears" that some might, so take that into account.

Your Bandcamp purchase would net you tracks in MP3, OGG, or FLAC formats, which would let you specify higher bitrates (FLAC being lossless).