My best friend, who is studying to be an 
archivist, recommended archival supplies from 
www.gaylordmart.com. She says that all the major 
libraries and special collections that she knows 
of order from this site.

According to her, most of the supplies at this 
site are "safe" for storing important papers, 
photographs, and more relevantly, cels and cel 
sketches. 

Though the supplies may be pricey, you may find 
that the quality and manageability that they 
bring is worthwhile. They carry albums with 
pages that are quite large, for example:

Album (24H x 16"W):
http://www.gaylordmart.com/adblock.asp?
abid=1582&sid=BD49FF3BFD214B31946410AEB8E895

With protector pages:
http://www.gaylordmart.com/adblock.asp?
abid=6389&sid=BD49FF3BFD214B31946410AEB8E895&sear
ch_by=number&search_for=OSMP

Prices vary with size, think of it as a good 
long-term investment. Hope this helps ^_^

--gracie