I'm planning on making games for money
And I'm trying to figure out the best sound API that's free for commercial and non-commercial usage

FMOD is free for non-commercial usage, and it's awesome. OpenAL has an LGPL license (so you can use it for free) if you use version before 1.1. irrKlang is free for non-commercial use.

Those are all the sound libraries I know, and OpenAL is the only free (for commercial) one I know of (so long as you use the older version).

SFML has a very nice cross-platform sound API, and it's in theory fine for commercial use. However, I will warn that some people are dubious about the licenses of the audio dependencies - YMMV.

There's also always the option of rolling your high-level functionality, over a low-level abstraction like PortAudio.

There's also SDL_mixer if you're using SDL.

Wow, I hadn't realised that OpenAL had turned proprietary - this is also a problem with open source development (since even if you personally aren't trying to make money, commercial use is a requirement for anything to pass as open source), and for similar reasons, OpenAL was one of the popular libraries for doing sound on Linux. I wonder what is typically recommended for Linux programming these days?

Wikipedia mentions OpenAL Soft as an open source alternative, but I don't have any experience of that myself.

5 months later... has anything changed? Or are these (Fmod, OpenAL, SDL, PortAudio) still the only decent options available? All of them have downsides, there's no clear choice here...

I'd say SDL and PortAudio are still the best non-viral open source alternatives, and I've had pleasant experiences from integrating them on Windows/Linux/OSX. Obviously SDL has a fairly heavy footprint so I can't recommend it if you're not using it also for input & video. Note that SDL 2.0 also supports iOS and Android.