For inexpensive plain backing I like 108” unbleached or tea dyed muslin. I’ve found it at JoAnn fabrics but others carry it as well.

Dream Cotton from Marshall's Dry Goods. I buy it by the bolt. $2.45 a yard. I can't tell any difference from Moda Bella. Online the bolts are 25 yards. Dream Cotton comes in 108" in 15 yard bolts for $4.50 a yard. I live close so can find smaller yard bolts to buy. They are all mixed in. Reps don't have time to search for different size bolts so keep the 25 yard ones ready to ship. To buy a bolt call a rep. No tax ID needed. To buy yardage, order as normal.

I just checked and Marshall's is out of white, cream, black, gray, and most of the other colors of Dream Cotton. I was there in late February and the warehouse was full of the colors of Dream Cotton. Wow.

With so many people not working right now, I'm sure that's the case with a lot of stores. I know I've looked at several online stores that are out of all kinds of neutral solids.

I find I get a better deal buying backing fabrics and use them backgrounds or just parts of my blocks. They may seem expensive at $15-$25/yd but when you consider you're getting 3yds across x 1yd down, now its not so expensive.

I bought Moda cream and white in 108" wide from my LQS. Very nice fabric.

I like the extra wide fabrics for backings and or back ground fabrics. I used to keep it on hand but finally figured out it is easier just to order it when I need it, then I get the correct amount and the color I need.)

My first go to is Marshal Dry Goods, their prices are very good, they are fast service, and I have never been disappointed with their fabrics. And then it is Fabric.com - for the same reasons. (I do like to buy my fabric so that it can be washed and dried before the quilt is put together.) The place I use for quilting thought it was funny when I bought her fabric, then took it home and washed it. But I was going to be doing the binding and the chemicals on fabric destroys my fingers and fingernails, so she understood. Not sure why the batting doesn't bother me hands - but it's probably because I don't hold onto it like the cotton fabric.