Yes, check with as drapery shop. They have access to the right type of fabrics, at least the one I used to work for did. Maybe they will sell you yardage.

My mother used to recycle our old sheets and got lots of pillowcases out of them. Also, it's possible that you might look in the Home Goods type of stores for oddball sheets. Many times they turn out to be cheaper than purchasing fabric by the yard.