Sorry about your experience. You should have tested his skill before employing. You cant just randomly go and hire people because of their nationality without testing their skills. Your HR dept needs classes.
I don’t think it’s a question of Nationality. It’s a demand/supply/quality issue. If there are numerous Nigerian developers that are good/affordable then why not? The market will always move. There was a time that we all relied on foreign musicians and films for entertainment until nollywood/naija entertainers stepped up their game and claimed market share
PS: A brother, on radar, dropped a link to his app pricing website. For a simple Phonegap app with notifications, his website calculated $24,000 (=N=7,680,000) at 320Naira to a dollar. No body has time to be pricing with such clowns when there is a sanjay or gupta somewhere that will do it efficiently for $800 dollars and be asking for more work?.
Reference: http://radar.techcabal.com/t/how-much-do-you-charge-as-an-app-developer/2251/8