Oi oi, pay attention people! I posted at least half a dozen
links - oh, the archived threads aren't here yet. Fine fine
:P 


Where I Bought Backing Tissue (Optional)
(acid-free, buffered)
http://preservesmart.com/

Where I Bought Mylar D Bags
http://nt.bnt.com/talas/menu.html?category=109
(They also have tissue, I found out later; bewarned the
Mylar polyester bags are EXPENSIVE, about 1.50-1.60 per bag, 
I got them because I wanted to protect my better cels)

Where You Can Get Polypropylene Bags (Cheaper)
http://www.IconUSA.com/Onlinestore/sleeving.html
http://www.dandlproducts.com/mylars.htm
(Haven't bought from either of these places.)