Some stats, for what they're worth, as of 8/11/14:
In bidding for the third rat, $100 worth of leeway, contestants have been in the range 38 times, and outside of it 14 times.
Out of 156 possible rats, contestants have earned 87 of them (55%). With the above stat, that means 44% of the rats came from the third item.
The game has an overall win/loss record of 16-36 (a win being whenever the contestant wins the car).
-Jason