Here's a link to the place online where I purchased mine:
http://www.bblackandsons.com/
Prices have gone up a lot since I bought it, but I think it's still a lot cheaper to buy in quantity this way. I think this fusible is 60" wide, and I actually liked it better than JoAnn's as it seemed a little thinner.
Do a search on the bblack website for "fusible tricot" to find the yardage. It's $3.95 a yard for 60" wide now. Can order it in either black or white.