Sorry, Linda -- for new shopping I actually bought a couple of backs in the last couple of months. I was surprised to find some very reasonably priced extra wide yardage at my normal first stop of equilter.
With no sales or coupons, $12.95/yard for 108. Still brings you in the $20ish range but not bad.
https://www.equilter.com/product/285...-quilt-backing
I think if you order $100 or more you get a 10% off your next order thing...
When Joann has the great 50% off coupons but the entire store is already 33% off so you can't use -- often this is when you can get their extra wide pieces with the coupon!
edit: Even at thrift store prices, I sort of expect a back to cost about $20 or at least that is my goal if I can't get it out of stash and my stash is (finally) getting pretty empty of large yardages. I'm typically paying about $2/yard currently at the thrift stores and many times I go out and come back with nothing. And other days I make up for that. Hubby and I do it as part of our date day, he works usually 6 days a week and on Sunday we would go bowling (closed for covid but open again, unfortunately now its my knee) and stop at 2 thrift stores on our way home from bowling.
Having said that, I was shopping for a really nice back and ended up with a digital print at about $25/yard. Oh my goodness!