John,
It's expensive. Dont quote me 100% but the Mozambicans consider a quadcab to be a "luxury car" so the import duties on it will be 51% of the value of the car. You'd do well to contact a customs broker here to get firm information before you ship it. If you want the name of some guys who do that send me a message and i'll put you in touch with them.
That said, cars are really hard to come by in Pemba. I had to go down to Nampula to buy mine...the ones down there are all second hand cars brought in from Japan. A decent one, first owner in MZ will run you around USD$11,000-USD$15,000. They're cheaper in Maputo with a better selection. The car dealers there dont have websites and whatever stock they have on hand is what you have to choose from, but there are folks who (for a fee) you can send your "wish list" to down in Nampula. They'll go around to the different lots, take photos and descriptions, and send it to you. They can even broker the deal for you and deliver the car to Pemba. Saves you quite a lot of time and energy. I can get you their info too if you'd like.
I dont know what your numbers are like, but I hope it helps you make the decision.