I bought the shortest yardage possible for my block width. Not every fabric store will cut that small though.
Make trades with your friends, quilty and other. Lots of people have fabric and you don't need much.
Check out the remnant bins, too.
If anyone finds a specialty manufacturer I will be interested as well. It took years to collect the fabric for my first I-Spy and now have more on the planning table which will need more additions.