In Ontario Canada, buying single sheets is not a problem. I buy them for quilt backs all the time, both for my own use and for our guild's Community Projects. I buy them in quantities when on sale ($5 - $10) and can get them in cotton or flannel. My local Giant Tiger (small town department type store) often has seconds (even name brand ones made in the U.S.A., not just the made in Pakistan of China). I also buy them regualarly at Len's Mills stores, Sears and occassionally Walmart (quality is sometimes an issue with loose weaves and low thread counts). I try always to buy King or Queen size so that I have plenty of fabric. My 22 year old son who was with me on my latest sheet buying expedition commented "Mom, how many mis-matched sheets can one family use anyway?" Happy sheet hunting!