Hey folks at PBS, I hear you're having funding problems. Might I suggest taking a spin around the Web to find content released under a Creative Commons license that you can broadcast for free? The Creative Commons site has a content search engine, as does Yahoo!
It doesn't look like there's a whole lot of video just yet, but Jason Scott has just released his 5 1/2 hour-long documentary series on BBS technology and culture under a Creative Commons license. The series is not going to cost any money to acquire beyond the $50 the 3-DVD set costs and from what I hear, it's an interesting and professionally produced view of a topic that many in your potential audience might be interested in watching.
And perhaps it's time to make the Public Broadcasting Service into just that...media by the people, for the people. A nationwide public access channel that draws the best citizen content from around the country and (this is the important bit) is edited into PBS programming. Or at least take a few hours out of the week for this...I don't want to see Frontline, Sesame Street, Nova, or Newshour with Jim Lehrer taken off the air, but giving the Make magazine gadgeteers a half-hour a week to geek out about hacking stuff seems reasonable. The overall result may feel less professional but a lot more participatory.