"It's killing my business," said Mahmoud Sani, who runs a rental car business in Kaduna. "But if we don't buy on the black market, our cars will not be working but waiting in lines."
Even ordinary Nigerians are cashing in. Soldiers, police officers and government officials are among the people buying and reselling gas.
Last week, men driving cars with government license plates traded barrels of gasoline in the parking lot of the Public Enlightenment Department, an arm of the Independent Corrupt Practices and Other Related Offenses Commission.
The activities seemed to irk Mike Sowe, the head of the agency, which sponsors anti-corruption campaigns.
Noting that Nigeria recently helped Liberia and other troubled neighbors with their affairs, Sowe said: "In Nigeria, we export what we don't have -- democracy -- and import what we have -- fuel."
Government officials have ordered independent marketers to send all available gasoline to filling stations, not black marketers. But even Obasanjo said he knows that could be a difficult assignment.