Exit polls as they are conducted currently in the United States cost somewhere around $10M (see
http://www.washingtonpost.com/ac2/wp-dyn?pagename=article&node=&contentId=A51692-2003Jan13¬Found=true about halfway down the page) and are not designed to predict the outcome of the election or to verify the non-fraudulency of the election.
(see
http://election04.ssrc.org/research/InterimReport122204.pdf)
A German-style exit poll that would be suitable to detecting fraud would cost about $80 to $160 million - judging by the methodology used and comparing the sizes of Germany and US. (see
http://www.mysterypollster.com/main/2004/12/what_about_thos.html for the description of differences between the two types of exit polls) and would still not be as accurate, due to the US high non-response rates and the fact that German Census bureau does official demographic surveys inside polling places and nothing like that exists in the US.
Here is what is needed to change US exit polls to the much accurate German model:
* Increase sample size by the factor of 10 to 12
* Increase the number of interviewers by the factor of 20, and increase their training
* Change laws in the US that would allow exit pollsters to be present at the immediate exit from the polling place, and not some distance away
* Do exit polling through the whole election day, currently there are gaps in the middle and in the end
* Somehow increase response rates from the current below 50% to 80-85%
* Have the government conduct demographic survey of voters INSIDE the polling place
Some of this takes money. Some needs legislation.