For those of us who feel that everthing should match even in a crazy guilt .I find the best way to get over the fear of not matching is to put a bunch of fabric scraps in a bag. Pull out a piece of fabric and sew. Don't try to make it match. I know its hard but It works well. The chances of getting the same piece of fabric is slim if you mix them well.
If you really have to match I find the stack and wack crazy quilt methed is the way to go