Hi there.
As I have seen, as soon as the foreigner show out for Ghanaian people, you might expect the price jump 5-6 times more, therefor, it's advisable don't show out yourself in the scene at the begging, just send Ganian guy to ask instead, as soon as you know the initial price , you can go ahead of negotiation by yourself.
Unfortunately, this is the truth here, moreover don't forget to ask about the electrical power, water supply with pumping machine, and sewage tank.
Regrads