i'm not sure a study has been done. i'll look around. anyone who hasn't heard me speak out against the sale of drugs, i'll tell you now, i was arrested for distribution in 1993 and 1994. selling 1 ounce of weed to a cop has cost me in excess of 10 grand, personally. my assumption is based on personal experience. anyone who also doesn't know. the police use confiscated drugs and have informants sell them on the street to catch people buying. that same in informant may sell the same crack rock 10 times.