Here in Nothern VA there are a couple of sources.
I remember a woodworking/turning friend mentioning he gets wood from these folks. they list red cedar.
http://www.freestatetimbers.com/
stock_western_red_cedar.html
Here is another source he uses. They carry red cedar
http://www.exoticlumberinc.com/price_list.php
He also gets wood from these folks. Not sure they carry red cedar though.
http://www.dunlapwoodcrafts.com/
You might also try these people. I found them doing net search.
http://www.bearcreeklumber.com/species/wrcedar.html
Have you tried the Western Red Cedar Lumber Association (www.wrcla.org/)? They may be able to put you intouch with a more local source.
Hope this helps with your project. Good Luck