That is the main problem with iphone:
to get Iphone 4, you paid 400 bucks (200 + 200)
When iphone 5 will be out very soon, you will have to pay my be 500 bucks, and it goes on...

Iphone  is one of the best phone in the market, but I am happy with my 3G android Also not worth moving to 4g spending such a huge amount...