I was just at JoAnn Fabrics and they were out of all the brands posted here so I got this one. I called the manufacturer and they said it is 100% polyester with no flame retardant additives and sent me a MSDS sheet on it.
Joann does not carry the $5.99/yd version anymore.
I recently bought the $6.99/yd version, and I think it is better than the $5.99/yd version.
The $8.99/yd version, I think is ok to buy a yard or two until they have the $6.99/yd version back in stock.
if you are not in a hurry, wait for the 70% off coupon and buy the whole bolt (10 yards). It will last you forever.