By comparison, a non-death penalty murder case in nearby Lubbock County typically costs about $3,000, court officials estimate. The average cost to house an inmate in Texas prisons is $47.50 per day, according to Michelle Lyons, spokeswoman for the Texas Department of Criminal Justice.Thus it would cost about $17,340 to house an inmate for a year and $693,500 for 40 years, far less than even part of the death penalty costs.The regional public defender's office estimates that just the legal costs for a death penalty case from indictment to execution are $1.2 million.ounty estimates in Texas indicate that the death penalty system is much more expensive than sentencing inmates to life imprisonment. Gray County spent nearly $1 million seeking the death penalty against Levi King, even though he pleaded guilty to murder.