If you just need lots of music, most of which is quite good:

http://www.gamemusicbundle.com/

It's anything over a dollar for the five headliners, ten dollars for the full pack and some of the more interesting albums in the bundle for me, and another five if you want to add the first indie music bundle to the mix.

That said, I would have paid ten dollars for the Machinarium soundtrack alone, if I didn't already have it. Great album.

Speaking of Machinarium, the creators of that soundtrack have recently released another album:

http://store.floex.cz/album/zorya

You can listen for free there, and buy it for your MP3 player if you so choose.

Following their recommendations and inspirations:

http://sonic.eleventigers.net/album/111

Again, listen for free, and that album is a choose-your-price if you wish to buy.

Or, if you want a bundle that's less strictly instrumental:

http://www.indiegala.com/

That one gets you both games and (completely unrelated) music for varying prices. I got the middle option and, even being unable to play many of the games, feel that I got more than my money worth.

Anyway, that's some of what I've been listening to lately, and the reason I am now broke. :P
Hope something among it speaks to someone out there.

Cheers, everyone!