I would suggest trying to hit Cool Cottons and Fabric Depot. At Cool Cottons you'll see some more obscure imported fabrics, but you'll have to bus instead of max. The Tri Met website will navigate pretty accurately.
At Fabric Depot you'll just find alot. If you're going n a weekend before 6 they have their outdoor sale now which has a bunch of $5 a yard fabrics. They're also open until 9PM so it should There are a couple of corners that its easy to miss. The batiques blend into the bridal section bad some of the quilt cottons do too. There's a Managers Special sale rack that I see as the dividing line that's easy to miss. The flannel and Minky are surrounded by quilting fabric. In the back corner by notions and home dec I the remnants section which has good stuff too.
Can you tell I was there last weekend and used to live up the street?