Stealing the Election: Money breakdown
Bruce Schneier and Paul Kocher point out that the cost of rigging the election with broken voting machines would be cheap
Let's try another analysis: What is it worth to compromise a voting machine? In contested House races in 2002, candidates typically spent $3M to $4M, although the highest was over $8M. The outcomes of the 20 closest races would have changed by swinging an average of 2,593 votes each. Assuming (conservatively) a candidate would pay $1M to switch 5,000 votes, votes are worth $200 each. The actual value is probably closer to $500, but I figured conservatively here to reflect the additional risk of breaking the law.
If a voting machine collects 250 votes (about 125 for each candidate), rigging the machine to swing all of its votes would be worth $25,000. That's going to be detected, so is unlikely to happen. Swinging 10% of the votes on any given machine would be worth $2500.