"This study found that the savings of supply-control programs are smaller than the control costs (an estimated 15 cents on the dollar for source-country control, 32 cents on the dollar for interdiction, and 52 cents on the dollar for domestic enforcement). In contrast, the savings of treatment programs are larger than the control costs; we estimate that the costs of crime and lost productivity are reduced by $7.46 for every dollar spend on treatment."
Rydell, C.P. & Everingham, S.S. Controlling Cocaine. Santa Monica, CA: Drug Policy Research Center, RAND Corporation. 1994.