From a pure incarceration standpoint executions are cheaper.
The actual price of an execution is extremely cheap. I think the drugs cost something like $90. And the costs of personnel and such surrounding the procedure aren’t that high an increase from the day-to-day operations of a prison.
Typically death rows are prisons where each prisoner has his own cell, and is under almost total isolation from other prisoners.
They receive all their meals delivered directly to their cell, and have individual work out areas.
This arrangement means that for the average of 8-12 years (rough average for states that have the death penalty and are truly active in its use) a prisoner is on death row he costs more per year, just in incarceration costs, than a regular prisoner.
Over a life sentence, though, the lifer in prison serving say 30-40 years costs more in pure incarceration costs.
The cost of lawsuits imo isn’t really something we need to factor into the issue. Nor is the price of executions.
If you believe that the government has a right, or that justice requires, a death sentence then the cost shouldn’t really mean anything.
Furthermore if you are against the death penalty for moral reasons trying to base that decision on the cost of the process is fairly shallow in my opinion.