"What do you figure the cost per person is for this program" No idea, but probably a substantial amount. Wild guess: $100 a day? "and who would pay for it" depends upon the circumstance, but a mix of funding sources. No idea what percentage of public/private funds. "if we were to propose that we build enough of these facilities to cater to all the drug users in the U.S." undoubtedly we already have many facilities at substantial cost.