i find flat sheets at Ross and Marshalls all the time and I have good luck at my big box store, they have seasonal flannel sheet sets that go on clearance regularly. I save the cling sheets for FMQ practice and use the flats for backs. I gave the pillowcases away or use them for practice too. I'm also working on using up fabric for quilt backs that I'm not super fond of anymore, or I give it away to someone else to love. I've only bought one bit of fabric for binding and two bags of scraps for a quilt for my child so far in 2018 which is a record for me lol