Big Als was good for a few things! First time for me this year that I didn't stock up on salt on Boxing Day too. I'm in the same boat, I use a lot of this stuff on my FW tank and I don't have much left of my current roll.
Someone once told me they were getting their filter floss at The Sleep Boutique (not far from where UFA used to be). But I never followed up on that myself, so I don't know for certain. Bt could be worth a visit. Link -
http://www.sleepboutique.ca/custom-specialty-foam/ (in th epicture you can see something that looks like it could be the right stuff..)
Anyhow if you find a place please post where you got it. Thanks!