Here is an article on falling drug prices from MedicalXpress.com. It is based on this paper that was recently published in the British medical journal, BMJ Open, by Werb, Kerr, Nosyk, Strathdee, Monaner and Wood. The authors note that prices of heroin, cocaine, and cannabis have mostly dropped from 1990-2007, but there have been some price increases in heroin and cocaine from 2007-2009, though prices of cannabis have continued to drop over those two years.
Why have prices fallen over these years, in spite of law enforcement making every effort to curb the flow of drugs? Could it be that demands for these drugs have fallen, especially as buyers may be switching to other drugs, such meth, ecstacy, and other drugs? Or, could it be that the authors are correct in supposing that there is a drop is supply? What extra information would you want to know to make you sure that either supply is increasing or demand is dropping up to 2007?