Here is a link to quilt shops listed on the Pine Tree Quilters Guild (The Maine Guild) web site:
http://www.mainequilts.org/quilt_shops.htm
All of the fabric shops in the above replies are wonderful. Another great shop is not exactly on the coast, but a short distance off I-95 in Madison, Maine. It is called The Fabric Garden and this place is unbelievable. It is a small building but the amount of fabric they have in there rivals any of the larger shops and is fabulous. If you are into reproduction fabrics be sure to go to the Busy Thimble in Litchfield. She specializes in fabric from the 1800's and has hundreds and hundreds of bolts. Another small building but you will be amazed when you get inside. When I lived in Maine, up until a year and a half ago, these were to of my favorite place to go, other than to Marden's, for deals of course.
PS: Maine has a wonderful quilt show every year the last weekend in July. 300-500 quilts, nationally known teachers and fabulous vendors from all over the country. It is in Augusta (the capital) in the air-conditioned civic center.