Contact your local quilt shop. They will be able to give you a couple of numbers to call. Every Long Arm Quilter has their own way of doing things. You usually supply the backing and sometimes the batting. Around here they charge from .01 a square inch to .05 a square inch. The least expensive way to go is a edge to edge. Custom quilting gets very expensive. I a throw that I paid $225 for custom work. I have a queen size that I paid less than $80 for edge to edge. They are both beautiful. Expect 2 to 8 weeks turn around time for a good quilter....as word spreads. When you find one you love keep her as good ones are hard to find.
Connie