Dear Bingley: there is a site called "Carolyn's Coerner" with a lot of information about the spelling bee. They had three sets of words differing in frequency of usage. But
I have been surprised to find quite a few fairly common words inclided in what is supposed to be the least frequently used list. They apparently use a search engine that gets some really stupid coinages that I think they should have discarded. I'll go get URL to Carolyn's Corner.

http://www.spellingbee.com/cctoc.shtml