So, the cotton-spinning thing didn't go away overnight.
Pollywogs Yarn and Fiber, and since they're based in New York, I assume that I bought it on eBay. I also assume that I bought it a long time ago, since the 7.6oz bag only cost $7.13. It's labeled as "Butterscotch Swirl".
I spun up two full bobbins of it, which I plied to a fine commercial cotton yarn. The pair came out to 328 yards of mostly fingering weight yarn (total weight 3.7 oz right now, but they're still damp. Cotton takes a long time to dry).