How much will I get if I sell my black iPhone 4?

My 24 month contract is coming to an end in the next month. I want to sell my iPhone 4. I've never dropped it and it has no scratches on the screen, as I have always had a screen protector on it. There are only light scratches on the back, due to normal wear and tear. There's nothing wrong with anything about it, never had a problem. How much will I get for it?

(I'm in Australia.)

I'm in the US and a good and fair price for your phone would be $350-$400 (US) depending on aesthetics

Here in the USA companies like RadioShack will buy back electronics and give you Credit to buy other products in their stores.

I looked up the iPhone 4 with 16G, and the estimated price was $150.

There should be stores in your neck of the woods (area) that buy and sell electronics too, like electronics firms and game stores, try them.

Try Best Buy if you have one in Australia. You can trade your phone in and get a new one right there. I'm not certain what they give for the 4 but when i traded in my 4s they gave me 250