It is the same in every business! I remember how much free work we did when we first started our business. And almost without exception those free jobs NEVER resulted in money. Whatever they pay is how much they value your work and once you agree its value is nothing...well, there you are!

I even disagree somewhat with the disclaimer above about charity events! The charity employees who run the events typically get paid a salary. And they know that running a successful event always costs money (even though it would be nice it everything were donated usually that ain't the case!) You should at least get all your costs covered and you should get plenty of free promotion.

Bottom line...don't work for free unless it is just about having fun, helping out, etc.