Yini,
I have brought in both new and used appliances on different occasions. Each time, I was charged duty based on a "list" that customs has for different items. It does not depend on what you paid for the item, they charge the set rate for each thing. You can never find out what the official rate is until your appliances get here. By then, it's too late.
For example, I bought a DVD player in WalMart a couple of months ago for 39 dollars. The tax here was almost a hundred dollars. At the airport, there is a hugh room full of stereos, DVD players, and other items that people have had to abandon there because they were unable to pay the taxes.
Each time I brought something in, it was more expensive with the local taxes than if I had bought it here in the first place.
My suggestion is that you sell whatever you have, and buy it all new here.