I have been to the quilt show in Augusta, Maine. I was very impressed, but have only been once and only to that one, so do not know how it compares to others. I did not get to go last year.
Two of the listed fabric stores I have been to are Cottonweeds and Calico Basket. Both are great. We also have a surplus store in Maine called Marden's. They carry quilt shop quality fabic. You can't go in there looking for something in particular, but I have gotten great buys there. Their web site addy is:
http://mardenssurplus.com
Not sure what areas of Maine you are going to (besides Augusta), but the Portland store DOES NOT sell fabric because they are in the same strip mall with Jo-Ann's fabric. The website gives a map of all the stores. I have only been to the ones in Lewiston and Sanford. You might want to call them before going to make sure that they carry fabric in that location. Their price for their fabric ranges from 2.69 to 3.99.
I hope you have a great time while you are here.