Growing up right after the Depression I learned the old adage of "Waste Not - Want Not"...
This may not be of much help in your particular case as I do 3 gal batches, but I use Tight Nylon Mesh Paint Strainer bags from Home Depot. I've heard others say they do 5 gal batches using them though.
I have been doing BIAB almost 2 yrs now, brew about once per month and am now only on my 2nd bag.
Home Depot sells the 5 Gal. bag in a 2 pack for $3.97 American. I see Home Depot Canada has a 14 pack for $14.97 Canadian.
http://www.homedepot.ca/product/dynamic-nylon-paint-strainers-19l-5-gal-12-pack/826728 They may also sell them in a 2 pack. I have never had a problem with them. I lost the first one as I used a metal spoon once instead of my regular wooden one or might have let the bag touch to kettle bottom when applying direct heat. Since then if applying direct heat, rarely, I hold the bag up slightly.
Also for hop sacks I just use regular 2 inch "cotton" stockinet. Since you would be boiling no nylon. They also sell it in 3 inch. I ordered a whole roll (25 yds) for $16.44 including shipping from Amazon. I cut to length and tie both ends.
Just my 2 cents.