Mardens in Maine is not a fabric warehouse but a general clearance center and the fabric varies from location to location. Still - a great place to shop for fabric in New England. Ryco Trim in RI is a warehouse of fabric but they do not sell online.
http://www.rycotrim.com/
My go to place for notions is J Hittle in KY. They have fantastic prices and are wonderful to deal with.
http://jhittlesewing.com/