iphone or to be exact ios (apple) have only one product/manufacturer so their price drop is slower then the rest of the phone

, just imagine if ios like android and have more then 1 manufacturer or more model. like sony/samsung/motorola/nokia/etc brand produce phone with ios as the main os, their resale value will be the same like android.
retail price for iphone is fix, while shop selling price is subjective.

other then that, blackberry phone one is good example imo if apple have multiple product. For an example curve-not so high resale value (middle/low end model), while certain model (bold series) is pricier.
btw same can be said for wp, imo their current resale value is worst then android, even price drop is faster then android.
Added on September 11, 2012, 10:33 am
marketing strategy if I might say so myself.
as for s3, currently I am using for surfing+take picture/video (good enuf but kalah to my wife n8) and mainly can play game

a big upgrade for me since previously I am using x8/csl mi300

I waiting for iPhone 5 to come and settle down. After using htc one x so called quad core it's not a really pleasant experience.
Samsung can't do what iPhone do they only can copy and make hardware. If tomorrow android decided to stop their current updates and start a new OS . Samsung sayonara. Their bada is dead and it's worse than Symbian