In my experience, there's a lot of variance from project to project and client to client.
I try and remain flexible to the each project's particular needs, so until we discover the shape of our collaboration, I recommend starting with an hourly rate.
$ 110/h
Some projects have taken me as little as 3 hours; others I'm still working on hundreds of years later. All hours are fully itemized and accounted for, so you always know where you stand.
Once we've established a successful design relationship, I'm in a better position to offer flat fees that will accurately reflect the work involved.