6x C++ programmers (At least 5 years experience)
12x Artist (2d/3d/cinematic/concept) (At least 3 years experience)
2x Writers/Story (At least 5 years experience)
2x Leaders (1 as Idea/Creativity & 1 as Budget/Focus) (At least 3 years experience)
?x Musicians (only for 2-4 months needed)

That would be a good setup, for a small/mid sized RTS game or FPS game.

MMORPG games cost more due to time, more people, and guess what TIME!


Side notes:
Also it doesn't matter if you have 500 people or 40 people working on the game. its actually better if you had around 8 programmers (experienced) and a lot of good artists (around 14) cause that's how you get good quality stuff.