I agree that that is a very reasonable price. I have a friend who does custom quilting for me on occasion when the quilt I have needs that sort of expertise. I know she is very experienced and will think of things I never thought of, so I usually give her freedom to create something wonderful.
She recently custom quilted my "Bears in the Woods" (Eleanor Burns pattern) for me. She quilted a bear outline on the top, bottom, and sides in open areas, feathers and curls, and quilted lines in the trees. It is all done by her manually moving the longarm machine - not a pantograph. So, I think it is very reasonable.