Is there any other hidden charges for your visa apart from 5000naira

I am surprised at the fact that agents and people always say to procure visa to china will cost not less than 200,000 nairas or more. While you categorically stated in answer to a question that it cost only 5000 nairas. Please clarify me more on the actual sum to be paid when someone is travelling to china to buy some goods. It is my first time and i do not want to be duped.