I saw at american cinematographer , there was big light source filters. There were tens of different colors come in a catalog like pantone or printing press paper selection catalog.
Go to gigapedia.com and search american cinematographer in database. After finding the issue , select links and download.
I found JAN 2009 .
http://gigapedia.com/items/255488/am...--january-2009
click on links and download.
May be there is cheaper gel filters or you like light source filters.

Best ,

U.