The Nigerian currency exchange market is interesting these days. Results show that the naira is trading lower than the dollar, so if you have a couple of hundreds of dollars you want to exchange for a dollar, you can expect good returns.
The exchange rate at the black market between the dollar and naira shows that today, 20th of April, the naira sells for N435 to $1 at the official market or CBN rate, while sells for N590 to $1 at the parallel market or black market. You can buy it at N587 for $1 today.