This is the best that I can come up with as far as
container-wise.  They are archival and seem to
come in the right sizes.  The Blick Paper Storage
Box and Blick Metal Edge Archival Clamshell Box
are on sell right now I think.  The Century
Archival Art Storage Box is a little more
expensive but comes in more sizes.

http://www.dickblick.com/zz153/02/products.asp?param=0&ig_id=5695
http://www.dickblick.com/zz153/03/products.asp?param=0&ig_id=5703
http://www.dickblick.com/zz173/02/products.asp?param=0&ig_id=73
http://www.dickblick.com/zz153/01/products.asp?param=0&ig_id=5716