It is nonsense that artists won't do something for free (they may not be familiar with the concept 'open source', but will instead just do stuff for free). I'd even go as far as to claim that the large majority of artists do things for free.
I just think there is a massive communication problem: programmers and the large majority of artists are living in different worlds, and hardly know of each others' existence. You'd have to find out where artists hang out (depends on what type of artist you're looking for: musicians, cartoonists, painters), and see what they can do for you. Hint: don't go and suggest they program everything in 3d according to your specs, and deliver next Friday.