Hmmm…it must be inflation. Maybe the transportation cost of the drugs have risen due to the cost of gasoline:

Prices for cocaine and methamphetamine have risen for the fourth quarter in a row, a trend law enforcement officials say indicates supply has dropped.

The price for a pure gram of cocaine increased 47% since October 2006. The price of a pure gram of methamphetamine jumped 84%, says a report out today by the Drug Enforcement Administration.