If she is quilting :stitch in the ditch and it is Dear Jane I would say at least £100.
You say she is basting it why if she has a long arm and is quilting.?
I didn't think long armrest basted . They don't like people to take in. A quilt which is already tacked and ready for quilting.
The cost of the quilt will change the more difficult the work.
Most of the Laq I know also offer own fabric and wadding which then add to cost.
This is a large quilt. Can she do it on her frame. My friends at120" only just fit .
I'm trying to put a few different peoples experiences in one answer.