Best info yet!
40 years ago I was making stuffed dolls to sell. Pre-packaged polyester stuffing was quite pricy to get enough to stuff a doll firmly. I walked into am upholstery shop and asked. He sold me a BALE of scraps for $35. It just fit in the station wagon. Worked for me and I still have a bit left.
You can get a lot of info and good deals if you chat with the shop owner and explain what you want to do. Sometimes they give you the stuff for free. My long-arm-quilter person also gives me free scraps of batting.