"A key factor underlying the recent increases in rates of heroin use and overdose may be the low cost and high purity of heroin.45,46 The price in retail purchases has been lower than $600 per pure gram every year since 2001, with costs of $465 in 2012 and $552 in 2002, as compared with $1237 in 1992 and $2690 in 1982.45 A recent study showed that each $100 decrease in the price per pure gram of heroin resulted in a 2.9% increase in the number of hospitalizations for heroin overdose.46"

Source

Wilson M. Compton, M.D., M.P.E., Christopher M. Jones, Pharm.D., M.P.H., and Grant T. Baldwin, Ph.D., M.P.H. Relationship between Nonmedical Prescription-Opioid Use and Heroin Use. N Engl J Med 2016; 374:154-163. January 14, 2016. DOI: 10.1056/NEJMra1508490.