Had someone ask me to quote for the following:

256 page A5 handbook with 4 page cover

Also option of 164 inner pages.

It's a big job and I've not done anything like it before, even in my full time position.

I've got 3 years experience as a senior designer in my full time role and recently set up as freelancer in my own time but costing things stumps me a bit. I don't want to go too high and not get the job but dont want to go too low and rip myself off?!

help!