Check our how much you will earn from recontracting a IPhone and selling it.
If you would like to know how much your iPhone costs you for a 24 months contract from M1, Starhub and Singtel?
Or if you would simply like to know which iPhone model, color and capacity to sign to get the maximum profit, check out this webpage.
7 and 7 Plus Singapore Telco Pricelist combined
Hope it helps