Price for an iphone 4s/5 with upgrade?

I have a 16 gb iphone 4 right now and in august i can upgrade. How much IN AUGUST will i have to pay, trading in the 4, for a 4s? What about a 5? Both 16gb

The prices for them range from:
Iphone 4: $150-$250
Iphone 4s: $250-$350
Iphone 5: $400-$650

You'll probably have to pay $50-$150, although some people may ask for more, depends is the Iphone's are unlocked and what carrier and stuff.

With an upgrade a 4S is $99 and a 5 is $199.

With an upgrade, the iPhone 4S is $99 and the 5 is $199. They won't trade in your iPhone 4, but I recommend selling it on Craigslist for around $200.