You know what...
To keep peace in the family, I would let her buy everything! Plenty of thread, rotary blades, fabric and backing and binding with lots of wiggle room, and a bit of a chocolate stash.
Then I would say how bout xxx dollars and then you will have to send it to the long armer to quilt which would be about xxx dollars...if she balks, then tell her your price may be a bit negotiatable but the long armer costs this much "really"...
People don't realize what it "actually" costs to make a quilt regardless of size.
Try and have your cost substantiated like in a previous post.
Good luck....I wouldn't do it :?