I do it all the time. Buying 'cheaper' sheets works better because of the lower thread count. Not super thin, but you can have trouble quilting with the high count quality sheets. When Anna's Linen was still around, I would buy several of the basic colors whenever they ran their sales and use them for backing on charity quilts or throw quilts that I sold at a local shop. It really kept the cost down so I could sell them and make a profit. I would often quilt with a variegated or contrast color so the pattern showed up nicely on the backing.