I'm just guessing, but I believe directorik's advice (that you're not ready) is based on an assumption that the band who hires you would have some kind of real budget. Sorry if my guess is wrong, directorik.
Anyway, I would agree, no offense intended of course, that you're not ready to work with a band that has a real budget. None of them would hire you, anyway. But I do think you're ready to charge a very small fee to a band that doesn't really have a budget (and there's a lot of those out there).
As for the question of how much to charge -- I can't answer your question, but if you're in a similar situation as me, then maybe my experience can apply.
I do super low-budget stuff. I just produced my first music video (in fact, I'm typing this while taking a short break from editing it). A friend on Facebook got wind of my production, and contacted me to ask how much I would charge to shoot one for him. I told him $100 per full day of work (one day to shoot/one day to edit), if he just wanted something quick-and-dirty.
But again, that's only if he wants something quick and cheap and easy. He's a rapper. We could totally shoot, for example, a cliche rap song, in which the artist is driving around in a fancy car, and he performs to the camera with a bunch of dudes looking thuggish behind him, and girls with big booties are dancing in slow-motion, etc. Anyway, a cheap cliched video like that could easily be shot in one day, and edited in one day -- quick, easy, cheap. I personally have no interest in making that type of video, so I would definitely charge him for my time, and $100/day is enough to make the endeavor worth my time.
However, I also told him that if he's interested in doing something really unique, something creative, that would set our video apart from others, then I would do it for free. I told him what I would require from him is the commitment of a great deal of time -- much more than one day. With only one video under my belt (and it's not the world's greatest video), I see that I need to build a portfolio, so to say, so if somebody with quality music wants to work with me, I benefit simply by pairing up with them -- no money needed.
Either way -- good luck!