With 2 year activation at AT&T you can get a 16GB iPhone 4 for $199 or a 32GB iPhone 4 for $299. A data plan is also required, the minimum cost $15/month and gives you 200MB of data per month. You will also need a messaging/calling plan.
300
$200 with a two year plan
the 3gs is much better for it's money iphone 3gs is better, i think. but it is very dear. it seems that you have enough money. if not, you can buy cheap phone instead.
In the U.S a 3g costs $99 and the Iphone 4 costs $200
An iPhone costs about $US200-300 (On Contract)
Currently, on Sprint, the iPhone 4 costs about $99.
wait for iphone 5 and then get a 4 because they will be much cheaper
$299.99
The fee is 30 dollars each month for the Iphone.
I'm assuming this is old as the iPhone has been out awhile, but no there is no return policy with Apple or AT&T.
It does not exist yet the iPhone 4 does.
Probably less
Well it was said that the iPhone 5 would have a much thinner screen then the iPhone 4. Then the Iphone 5 would have more and better apps on it.