I'm still working on our new website and spent some time yesterday taking photos of extra wide backings (about 108" wide). Here are just a few of the more colorful ones. We probably have about sixty of them. In addition we have 6 or 7 in batik and even a few flannel (many of these are 100" wide). They average about $15 per yard.
For years all we could get was bleached and unbleached muslin. then shops like us (many with long arm machines) started asking sales reps for more and the fabric companies have really responding.
If you can find something you like, you will really save money for quilts wider than 42".

some examples:
60"X80" two lengths 5 yards @ $9 = $45 extra wide 1 3/4 yards @ $15 = $26.25
95"X110" three lengths 9 3/4 yards = $87.75 extra wide 3 1/4 yards @ $15 = $48.75

When the new site is up we will have many of our backing available on line. Or, if you email a photo of your quilt, we'll be happy to see if we have a wide backing for you.