iis campaign finance why politians get elected?

As of May 18, 2012, 545 groups organized as Super PACs have reported total receipts of $204,716,872 and total independent expenditures of $111,588,684 in the 2012 cycle.

http://www.opensecrets.org/pacs/superpacs.php

the US budget is about 3.7 trillion dollars

so

205e+6 / 3.7e+12 = 5.54054054 × 10-5

Super PACs will spend about .0055% of the budget to get their hands of the government pie

that's insignificant money by comparison

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further

I would suggest that publicity has more to do with news station coverage than campaign spending

one might argue that those well financed usually win
but the campaign may be well financed due to news publicity