For my coworker? Not free. He lost only three gallons of gasoline (his tank was mostly empty) but it cost $440 to replace his fuel tank.
This occurred between late Friday night of June 6, 2008 and early Saturday morning June 7, 2008 in the Oracle/Miracle Mile area of Tucson, AZ.
There is nothing to stop them from doing this again.
Recall my earlier post on this topic