Legalize drugs and use the money made from selling drugs to fund rehabilitation? I love it. And why not apply the same principle to alcohol and tobacco which are the most serious important addictive drugs to rehabilitate people from? The approach is far from polyannish. A great site which uses only facts and research to back up this type of drug policy is drugfacts.org. Go to the treatment chapter and you'll find this quote from a 1994 study on cocaine done by the RAND Corporation:
Domestic enforcement costs 4 times as much as treatment for a given amount of user reduction, 7 times as much for consumption reduction, and 15 times as much for societal cost reduction.
Treatment is way cheaper and more effective than drug enforcement and it turns out that the worst way to control drug use is to fly helicopter gunships around Columbia. Another chapter, compares The Netherlands to the United States, in terms of amount of drug use and the violence associated with it and the results are pretty significant.
I've been going through that website mainly over the last few days because I'm interested in using acupuncture and chinese medicine to help recovering addicts. Including these techniques the ones usually used, should make treatment even move effective and less costly.