To add weight to Joe Klein's suspicion that money matters less and less, The National Journal's Patrick Ottenhoff took the FEC disbursement forms, calculated the total amount spent by candidates in 2006, divided by the votes they amassed, and came up with how much each candidate spent per vote. "Richard Tarrant (R-VT) spent by far the most money on each vote ($85), while fellow self-funders Pete Ricketts (R-NE) and Ned Lamont (D-CT) came in second ($63) and third ($45), respectively. All three lost their races."
It's not that money doesn't matter, but particularly in primaries, particularly in smallish-to-medium states, the point where excess cash ceases offering significant returns is fairly achievable.