I can see it now.....I bet with this rumor the LSM are staging their reporters to Alaska. Sarah calls the radio show and announces, then.....nothing. No big press conference, no big rally. And the LSM are spending the weekend in Alaska looking for something to talk about!!
Every other GOP candidate would give their left testical/ovary for the free coverage and publicity she is getting without being a candidate. I think she should continue to tease the announcement for months, probably watch a few candidates wash out. After they have spent millions, she would only then have to begin to spend money under the oversight of the FEC (as I understand it - I may be wrong).
She could, with considerable fanfare, travel again to the radio show and announce there. FWIW, I am not convinced she is running.