I have a friend who uses tablecloths for backings. Another uses polar fleece for backing - no need for batting then. Buy the fleece when the stores have it on sale for $3 yard. It's 60" wide so there is more fabric to use.
When going through the closet to clear out older clothes consider using them in quilts. Check with restaurants that use tablecloths. They may be willing to give you their older ones or ones with tears or stains.