Where can I buy a Factory Unlocked iPhone in Singapore?

Do I have to order online from the Apple online store or can I purchase it from a shop. If so, can you please provide me with the location. And also is there any extra charges for an unlocked iPhone? I mean more than advertised on the Apple online store, Singapore which is 16GB: S$888 and 32GB: S$1048. Will I be able to buy the phone for these prices without any extra cost or contract charges from an Apple Shop?

Thanks in advance for your answers.. :-D