I carry Hobbs 100% Cotton batting in 90" rolls. Cost  is 30 cents per linear inch, .0035 x square inches, or $11 per yard.  I sometimes carry 100% wool and recommend it for large quilts since it is lighter in weight and nice and warm. 

I usually stock various large backings, around 108" x 108". Cost is usually about $45.  Below are photos of current stock. I also have a white on white floral, which didn't photograph well.
       Gold Marble
Gray Leaves
Dark Blue Leaves
Dk. Muslin Floral
Lt. Brown Floral
Off White/Black Floral
Tanner loves his quilt!
Why buy batting from me? Unless you have one of those famous coupons, I can beat the retailers' prices in almost every case. I carry top quality Hobbs batting in large rolls so I do all the lugging and you don't have to. But the best reason is that, in these big rolls, the batting is smooth and uniform. The packaged batting doesn't always lay flat which can cause lumps in your quilt no matter how carefully I keep an eye on it. 

Consider one of the batting types I carry for your next quilt.