It is advisable that you know where to buy things in advance of your going out. This can save you unnecessary exposure to touts. Nigerian Yellow Pages provides list of businesses, contact addresses and phone numbers and for shops and restaurants, your hotel can give you advise as well. When meeting businesses, the best thing to do is to locate the business, call their representative, who can give you detailed information on how to locate them.
At markets, you are supposed to haggle for your goods a notable exception is bread: its price is fixed. As a general rule, the real price is about half the price that was first asked. The seller may exaggerate the price when he or she thinks that you are a rich tourist ignorant of the real price. After agreeing on a price, don't walk away without buying, this is considered very rude. It is also advisable to go to the market with a friend you trust preferably Nigerian. That way the seller will know you can't be tricked into paying a higher price than normal.
Shops like supermarkets and restaurants will typically charge fixed prices. Fresh products and Western-style sit-in restaurants are quite expensive, with it not being uncommon to pay USD75 for a dinner per person.
important information on currency and credit cards
Nigeria's currency is the Naira NGN. Around April 2012 the rate was about USD1 = NGN157.
Generally, foreign credit cards are not accepted in many of the stores or even hotels in Nigeria. If you hold a Visa, MasterCard or Maestro Credit/Debit card you can withdraw cash in Naira from various ATMs in most Nigerian cities including Lagos. Visa machines can be found at Standard Chartered Bank. MasterCard/Maestro machines are found in Ecobank and some Zenith Bank branches however, most ATM machines accept both Visa and MasterCars/Maestro and are usually located within the premises of most big Nigerian commercial banks including their branches and outlets. Be aware that these machines only allow you to withdraw 20,000 Naira at a time, which is a relatively small amount in Nigeria. This means you will have to make multiple withdrawals at a time, and for each of those transactions you might have to pay a hefty Cash Advance Fee depending upon your bank policies. Also, most ATM's allow a maximum withdrawal of 100,000 Naira per day. Use Diamond Bank, who gives you NGN40,000 per withdrawal.
The best thing to do would be to buy Naira using foreign currency at the airports or near large hotels. Even here, only US dollars, pounds sterling, and euros are normally traded by these stores, or at least traded at a reasonable exchange rate. So change your home currency to one of these three even before you land in Nigeria. Changing large bills of US dollars or euros will give a better rate with professional money changers, such as on the currency exchange market near Lagos Domestic Airport. This is a walled enclosure with a large number of money changers, which is primarily used by local nationals.
Remember that these are not formal bureaux de change and you will need to negotiate the exchange rate. It is strongly recommended that you count your money in front of the exchanger, and don't be afraid to walk away if you are not happy with the deal. Be wary of your safety in money changing areas, and take care to make sure you are not followed when leaving them. There are formal Bureau De Change existing in the various banks, and you can be rest assured about transacting with them, although their rates may be slightly higher or lower than the rates outside.
It is advised to cash all your naira back into another currency at the airport before you leave Nigeria. The rate is irrelevant, as the naira is not worth that much outside Nigeria. In fact, you might not find any exchange office anywhere outside of Nigeria that trades Naira making them worthless pieces of paper once you come out of the country. Naira bills/coins may be of interest to currency collectors, but other than that, they will be nothing more than colorful souvenirs of your trip. Banks will change foreign currency to Naira, BUT USUALLY NOT THE OTHER WAY AROUND, EVEN THOUGH YOU ARE A FOREIGNER. You would therefore need to use the Bureaus de Change at the International terminal or the new Domestic terminal or street vendors to get foreign currency should you end up with unused Nairas at the end of your trip. A safe place to change in Victoria Island is in the tourist market of Eco Hotel in Victoria Island not the hotel reception which will give you rip-off rates.
If the Bureaus de Change at the airport do not want to help or are closed, the car park outside the International terminal is full of street vendors only to willing to change money from/into any major currency. When dealing with these street vendors, keep the money you are dealing with fully visible till the deal is finished i.e. don't put into handbag and later discover it is wrong and then try and bargain and count carefully with them, as they tend to try and short-change you with a note or two, especially when you change foreign currency into Naira which is a thick bundle of small notes, but with necessary vigilance are generally fine. Street vendors are also plentiful at the main land borders to change Naira into CFAs XOF (Benin and Niger side or XAF Cameroon side) if need be. XOF and XAF are freely and easily convertible to and from Euros at a rate of 655.957 sometimes with a small commission when you are in the French countries.
On Abuja and Lagos International Airport money can be withdrawn from ATM machine's. On Lagos International there are several ATM's, several may not function at all times. On Lagos Domestic Terminal there is also a functioning ATM in the domestic terminal on the 1th floor. Usually this a quiet ATM which also is very private and secure.
MasterCard / Maestro users can also withdraw Money from ATMs at several branches of Zenith Bank and GT Bank. Some ATM machines of Ecobank, First Bank and Intercontinental Bank also allow for MasterCard / Maestro cards. Look for the red ATM sign outside, or ask the on-site security officer at any branch. Also look for Ecobank, they have a branch within the premises of the Murtala Muhammed International Airport. Visa is however a safer option if you are visiting the French countries around Nigeria as well, as Mastercard/Maestro is close to useless in these countries.