For comparison, how much does a trial cost? How much is each appeal? How much does it cost to house a prisoner for a year?
I still think the taxpayers came out ahead.
Answer your own questions, come up with a figure. Oh and trial doesn't cost anything because the cost is a sunk cost already. Likewise appeals. The judges with their fat salaries, the court infrastructure, and judicial system employees are being paid for by the taxpayers regardless. There isn't any incremental cost associated with it. Incarceration is a real cost.