I would buy some inexpensive (like, $6 a bag inexpensive) poly batt from Walmart and just use that. I know a lot of folks like to use flannel but I tell you what - it's hard as heck to get nice tension with that thin of a sandwich. Flannel is cheap so it's a good alternative, but I'd spend a wee bit more and get a cheapie batt. Get low loft if you don't like that cushion...you can flatted it more with added quilting. You'll shave a lot of time and frustration trying to achieve and keep good tension. IMHO
For the record I'm totally not a batting snob. Unless it's going into a show I use those poly batts all the time.
