Steelbydesign:

VG is correct (of course).

But if this is the first time you do a freelance job, and if you're not yet planning the details of your own business, I'd say, yes, give a firm number. Or better, perhaps, two or three options. Outline what your client will have if she pays you $X, but for $Y she'd get all this and for $Z even this much.

Then, I'd also recommend sticking to both the tasks outlined and the price quoted. If this is a one-off experience, use it to think about your attitude toward independent work and all its details (including pricing).

But remember that there really is a difference between moonlighting and having a freelance business. I'm in the midst of teaching an online intro to business management to a group of people many of whom have moonlighted for years. I'd say at least half of them are discovering that a real independent business is *not* what they want.

Oh, and ... don't forget to get something in writing.