If you pledged at the 35 dollar level or above you will get a digital download of the soundtrack - I assume it includes the Kickstarter theme. If it doesn't there will be backers in the streets with pitchforks and torches.
At a guess, I bet there is a way to buy it either as a pre-order or on release. But I don't think it's out before release.
Also, I love that song too. I usually don't care about music in my game too much, but this one has me excited.
