Well, it looks like you need this gig on your cv. And the experience is... invaluable, really. I would suggest seeing what you can live with for now: 5,000?
Don\'t expect any other money than that which you get up to a month or so after the final mix. Any other promised deadline will, IMV, not be met. The bottom line is that many, if not most, independent features are labours of love. Sure, a few can make some real money from tv sales, and this one does have names, but chances are, there are a whole lot of people lined up to get paid before you.
A) Do you like the film?
B) Do you get along well with the director?
C) Do you think she/he has talent and will be going places?
D) Will you have some real say in the type of music you\'re going to write?
3 out of 4 should help you decide! ;-)