If your quilt has a pattern name, like lone star, try doing a search on webshots or photobucket. If you see one done the way you like, take notes on it and tell your quilter.
My LA'er has a book of samples, sorta like a wallpaper book. She has all her patterns sewed out so you can see what they look like. She should be able to talk you thru the different sections of your quilt.
Besides the price per sq.inch, you may also be charged for the batting and for thread.