officially launched iPhone 5C, 5S in Dubai. Meanwhile, some trusted vendors are providing it for a huge discount. The most popular place to get it immideatly is souq.com . They are offering an additional 15% off and now the iPhone 5C costs only around 2000 AED.
However, if you're looking for iPhone 4S. There is an awesome sale going on at www.apple.com/ae/ with the unlocked iPhone 4S for 1699 AED. That's a lot cheaper than any electronics shop in Dubai.
If you want to get the iPhone 5C directly after market launch then you can check out the Sharaf DG's online site or the www.store.apple.com/ae/. These two are the most trusted place to get an iPhone online. I've brought my Mac Air from Apple from the Apple's online store. I placed the order telephonically through their toll free number : 8000 444 0396. The telephonic support from Apple store is great, you get to talk with Apple representative directly and they stick with you for the entire process. If you dont want to get it online then you can visit some Apple resellers in Dubai.