How do you determine where in your range to quote for any particular gig? (Other than whether the hiring company is a nonprofit or not.)
All of these things will play into it . . .
1) How much money do I need?
2) What is the workload? (Is it just one week of work, but I know there are two weeks of prep attached it?)
3) Team Size - am I doing a lot of work myself?
4) Loss of income . . . if I am stepping away from a project to take on more work - am I getting paid enough to step away from the project?
5) Comparable rate . . . figure out what they have paid in the past for similar projects . . . what other projects that rate would pay . . .
6) Leave some wiggle room - so they can negotiate down.
7) Especially if working on a union contract - I want to make sure that I am compensated for not having an employer make health care or pension payments.

My value - what am I bringing to the table? If it's the type of thing I have done 100 times more, I may bringing quite a bit - if it's something new . . . then maybe I cut the rate a bit
9) Reimbursement for supplies . . .
10) Expected out of pocket expenses. . . look, there is often a weird combo of Pay + Per Diem . . . sometimes the per diem is so high, that I cut back on my weekly rate, sometimes there is no per diem, so I have to boost my weekly rate. Also, I may need to bring on an assistant to help me . . . so I am paying that, I want to make sure I am covering those costs.