Crafty, I'm in the Seattle area and we have such bounty at our stores here, it is unbelievable. When I travel, I do visit thrift stores in other locations and typically do find fabric somewhere around Linens or Crafts, I also look for unquilted tops/UFOs. Sometimes they are bundled into big or small bags, sometimes single lengths of yardage. I've also found entire bolts. You just never know. The going price is going up, somewhere closer to $2-3/yard, and I'm seeing a lot more small bags for closer to $6 which used to be the price of a big bag, which is now closer to $10. I do find a lot of early 80s mid-level fabric like Concord and Cranston, I also find pretty current Moda, Benartex, and top line designers.
The thing is, you can't just go out and hope to find the perfect piece for a project. That can be hard enough with a real quilt store. You have to be willing to collect and I have already collected.... You have to learn how to tell fabric content, a common method is "burn testing". Here's a pretty good article on that:
https://www.thesprucecrafts.com/fabr...fibers-2821302
There can be a lot of good usable 100% cotton fabric in a man's shirt, especially the back, especially in the XXX side of things!