I think finding fabric at that price per yd. (with a few exceptions) that will last the test of time would be difficult. The one exception to that rule for me has been to always be on the lookout for quality cotton sheets at thrift stores. I have been fortunate enough to come across some very pretty ones from Pottery Barn, Laura Ashly, etc. These are only one print of course, therefore more suitable for using as the back of your quilt. But again, you must consider coordinating the back with the front. Not always an easy task. But if you can make it work, it's a great savings.
There are many more 50/50 blends to be found in sheets with a pretty print, and when used for your backing, I don't think should be overlooked. Just my opinion. Would be interesting to hear what other's experiences have been with this.