How much can I get for my iPhone 4?

It's only 8gb

I will give you £15 for it. Inbox me!

$105 gazelle.com

I'll give you 75 bucks, or a $182.52 Xbox modded controller

Try craigslist for similar sells. Also eBay.

Not much because some phone companies are giving them away with a contract.

The best thing to do is to sell it on eBay with your desired price either as Buy it now or a Reserve.
There are a couple of things that will raise the value:
1.Is it GSM or CDMA ie does it take a sim card or not.
2.Is it locked to a network or unlocked
3. This sounds silly but, is it legal? Is the IMEI clean

For an unlocked phone, you could easily get anything from $200-300 easy

I suggest you visit www, cashforiphones.com to get an instant estimate on how much will you get for your iPhone!