Front page news today -- Apple threatened local sellers of hacked iPhones with legal action if they persisted with their sales. As a result, it's now going to be more difficult to find a hacked iPhone in Singapore... unless you know where to get one. And I don't, so don't ask me!
Note, though, that it's still legal to parallel import iPhones into Singapore. (Yeah, you can parallel import almost anything into Singapore, if it's in its "virgin" state.) So you should still be able to buy iPhones in Singapore, just not the hacked/unlocked ones.
Personally speaking, I used the iPhone a few times while on holiday in the U.S. and, seriously, the thrill dies after the third usage. That's why I don't plan to get one for myself. Besides, hardly anyone ever calls me on my current phone line anyway... (telemarketers don't count!)