Florida is an expensive state with many major media markets, making it easy for a self-funding candidate to become competitive by spending to raise his or her name recognition.

Voters in the Sunshine State have shown themselves willing to vote for self-funding political outsiders: Gov. Rick Scott (R-Fla.) won last year's primary by outspending the GOP establishment's choice, and did the same in his narrow general-election win.

Miller's soft spot in the primary could be immigration: He faced charges that he was weak on border enforcement in the 2010 House campaign. But if no other serious candidate emerges to LeMieux's right, Miller could spend himself into becoming the anti-LeMieux candidate, and win the primary.