No.
It does not say that you shouldn't covet your neighbors slaves. Go back and read it again. If you're going to try to "ad lib" your argument, quote the verse/commandment correctly.
"Never desire to take your neighbor's wife, his male or female slave, his ox, his donkey, or anything else that belongs to him."
Gods word translation of exodus 20:17.
Really? Are you going to attempt to argue that it costs MORE for someone to be put to death than to be put in prison for life and live that life at today's mortality tables?
According to a commission which studied it in america, yes. "The additional cost of confining an inmate to death row, as compared to the maximum security prisons where those sentenced to life without possibility of parole ordinarily serve their sentences, is $90,000 per year per inmate."