OMG! If you were not 2000+ miles away from me, I would be there to help you finish buying what they had left! LOL I have checked Goodwill stores before and found a little bit, but nothing that I would want to take home with me, that find sounds like a quilter passed and the family didn't know what to do with her stash. Shame really, but a beneficent to you!
As someone else said, quarantine the fabric, inspect it really well and if you can, hang it out to air, wash it or at least take it to a laundry mat, put it in pillow cases and tumble dry it on HIGH heat to make sure any creatures are not living in it. It may be totally fine from the donating person, but you never know what might have crawled into it in the back room of the goodwill and what hands have touched it as they have walked down the isles.. JMHO, but it still sounds like a great find! OMG I would have snatched it up in a heart beat at $1.99 a yard!!!