The Fiscal Times highlights findings from Vital Statistics on Congress related to the costs of running for office - among other things.
$1.3 
million: Average spent by 256 incumbents among 2012 winners 
who won re-election in safe districts (where they won with 60 percent of the 
vote or more)
$156,000: Amount spent by 
their long-shot challengers, on average 
$2.3 million: Average spending by 100 swing-state incumbents in 2012 who held 
onto their seats with less than 60 percent of the vote
$93,000: Amount 
spent by their challengers' campaigns, on average
103: House 
members from "swing" districts in 1992 (defined as districts where the 
presidential race was within five percentage points of the national result)
35: House members 
from "swing" districts in 2012 (the most prominent reason for the change is 
post-Census redistricting, which governing parties have used to draw lines 
favoring their side)