Hmm.. This is very much understandstable. However,, I would always say that every business is different even if it's similar or falls under same nature. The uniqueess of the vendor is partly one of the difference. And that's where marketing comes in.

Sice you as a person knows the quality of your product,, the sales logic is left on you.
Marketing differs and it's quite broud. Nevertheless,, in a situation as these,, manners, attitude,, patience and actions is highly recommended, and then a little bit of logic of reducing the price even if it's by 2naira difference..

In my opinion, nothing beats the force of a god marketer.