Ironically, one of the leading arguments against capital punishment is how expensive it is. Including all the legal costs of appeals and reappeals, it's approximately 1 to 3 million dollars per convict (in the US).
$1 million isn't expensive compared to 20-30 years in prison in the US.
People executed in the first half of 2025 spent an average of 24 years on death row. In practice, it's a life sentence plus execution. I believe the $1-3M figure is on top of this.