There are VTU(Virtual top-up) service providers that buys data from MTN and sell it to people who wants to resell(resellers) or directly to customers at affordable prices...
How To Get 2GB For 200 Naira – MTN Night Plan
Dial * 406 #
Respond by pressing 3 to select the MTN nightlife plan.
Then answer 2 to select 50 nairas for the 250...