Recently I saw a post about the Nigerian exchanges and i realized that the buying/selling rate there is 20-30% different that the EU and US rate.

That means that the people in Nigeria buy at +30%, BUT that also means that the Nigerian exchanges buy at +25%.

Simple math: Buy rate at BitFinex at 08:00 GMT = $915 Sell rate at Naira Exchange ar 08:00 GMT = $1149

That is a huge difference and it can surely be used for arbitrage.