I reserved a 16GB Black iPhone with Singtel at the Ngee Ann City hello! Store.
If you want an iPhone as early as it is available in Singapore [or as close to Singapore's launch day], I really recommend you go down to a hello! store to reserve a unit. You'll need to get a queue number under 'Special Events / Promotion' or something like that. Then, they'll be asking you a few questions.
Some questions that you may be asked include:
-Which unit would you like to reserve?
-Are you a current Singtel Mobile Subscriber? If yes, they'll ask for your mobile phone number, Singtel mobile registered billing name, etc.
-If you are on a contract with Singtel, they'll probably ask if you want to re-contract or keep your current plan. I suspect Singtel may sell the iPhone the same way as, say, a Nokia, in terms of the contract you'll need to get with the phone. [Data plan or voice plan, or both.]
If you want to predict how much you'll need to pay every month for the contract, I think the current service plans by Singtel OR your current Singtel Mobile bill is a good gauge for estimation [we have seen how the contracts abroad can vary from 'really good deal' to 'insane expensive', especially the data plan. So, don't bother looking at them.].
Personally, I really wish they'll bundle unlimited data for free with all their voice plans. But then again, that's just wishful thinking...