Archival Methods – http://www.archivalmethods.com/
Gaylord – http://www.gaylord.com/
Hollinger – http://www.hollingermetaledge.com/
Talas -://talasonline.com/
University Products – http://universityproducts.com/
American Frame – http://www.americanframe.com/
Frame Destination – http://www.framedestination.com/
Warehouse Framers – http://www.warehouseframers.com/
Clear Bags – http://www.clearbags.com/
Climax Photo – http://www.climaxphoto.com/wide_format_sleeves.htm
Portfolio and Art Cases – http://www.portfolios-and-art-cases.com/
Portfoliobox – http://www.portfoliobox.com/index2.html

http://www.archives.nysed.gov/a/records/mr_hrecords_cons_arcsupplies.shtml

If you have only one, it becomes precious; you may hesitate to use it fully.

No separation of tilting controls:
Vanguard SBH-300 (1.33 lbs supports 70 lbs) — $100
Arca Swiss Z1 (1.6 lbs supports 130 lbs) — $365 – $548. The double-panning feature here seems useless unless you do panoramic shots.
Markins Q-Ball Q20 (1.2 lbs supports 110 lbs) — $390
BH-55 PCL (2lbs supports 50 lbs) — $575

Separation of tilting controls:
Majestic 1001 Gearhead with 6×7" platform (no specs available) — $306
Manfrotto 468MGRC3 (1.8 lbs supports 35 lbs) — $329