The lady that encouraged me and taught me to hand quilt always used sheets for her backings. She even used poly/cotton blends as well. Her quilts are lovely. It was what she preferred and not an economic issue at all.
I learned to handquilt with sheets and I do think they were a bit harder to needle. Very doable tho. I will probably do it again but for now I have been piecing backings with my scraps and gifted fabrics. Just try it and see how you like it. Not heresy at all.