Each vote won by Democrat Cheri Bustos in Tuesday's election cost $38, compared to $48 for each vote cast for U.S. Rep. Bobby Schilling in the 17th District congressional race.
A staggering $12.1 million was spent on the race, the fourth most expensive in the country for the U.S. House in terms of spending by outside groups, according to the nonpartisan Sunlight Foundation.
Ms. Bustos won Tuesday's 17th Congressional District election by an 18,000-vote margin, although less money was raised and spent on her behalf than on Rep. Schilling's campaign.
Final fundraising reports for the election have yet to be filed, but as of Oct. 17, Rep. Schilling had raised $2.2 million and spent $1.8 million. Ms. Bustos was not far behind, raising $1.9 million and spending $1.4 million.
The really big money flowed into the district from outside groups, who put a combined $8.8 million into the election, the Sunlight Foundation found.
The $38 cost per vote for Ms. Bustos is based on the $5.7 million spent on her campaign - with outside money included - and the 150,575 votes she received.
The $48 cost per vote for Rep. Schilling is based on the $6.4 million spent by his campaign and outside groups, and the132,033 votes he received.
"That's actually pretty good," Western Illinois University political science professor Keith Boeckelman said of the $38 cost per vote for Ms. Bustos.
U.S. Rep. Joe Walsh, R-McHenry, who lost to Democrat Tammy Duckworth, had a cost per vote of $70 based on the $7 million spent on his behalf for just under 100,000 votes.
The outside money poured into the 17th District was fairly evenly split between the two candidates although Rep. Schilling had an edge.
According to the Sunlight Foundation, $4.2 million was spent by groups supporting the Democrat and$4.5 million by organizations that backed Rep. Schilling.
Republican operative Karl Rove's non-profit Crossroads GPS entered the race late and dropped $1.3 million on TV advertising in an attempt to sway the election in favor of Rep. Schilling.
The top spender in the race was the Democratic Congressional Campaign Committee, which spent $2.8 million, with most of that money funding TV advertising.
But It's difficult to say if the tsunami of advertising worked.
"A lot of people are arguing that you get to a point of saturation with the TV ads and people just tune them out," Mr. Boeckelman said.
Wealthy individuals, corporations and unions, freed by relaxed spending regulations in the wake of the Citizens United Supreme Court ruling, sent election spending soaring to unprecedented heights this year.
But much of that money was squandered on losing campaigns and some donors may now be experiencing "buyers remorse," Mr. Boeckleman said.
"I think it may be hard to raise this kind of money again."