Signing Time is no longer on PBS and you can read about it from its founder here.
Essentially no corporate or foundation sponsors came forward and the rules about public television advertising mean they could not direct viewers to the web site that sold their products. This in the age of DVR's.
Easy ways everyone can help include giving their videos and DVD's as gifts for Christmas and Birthdays and requesting that your library purchases the full collection.
Don't have a child with hearing loss? Well do you know one? Or one with late speech development? Maybe as a homeschooler you need a second language?
Our Homeschool co-op is teaching sign language and my Zoe just loves it!
And please don't overwhelm them with ideas of sponsors and grants (they've tried for three years) but DO contact them if you have a great lead.