How to Get a Free iPhone Upgrade (Even Under Contract)

1.
Brand new phones sell on eBay much better than used ones. If there's is a defect in your phone that the Apple store can't fix, they will replace it for free. If you've spent any time at the Genius Bar watching repairs, you'll notice they swap out far more iphones than they actually fix. Maybe the screen has some burn in, the battery life doesn't hold up, or the headphone jack is acting strange. If you're having any kind of problem at all, bring your phone to the Apple. They'll fix it for free or they'll give you a new one. Either way you're better off than before.
2.
Before you try to sell on eBay, unlock that phone for other carriers! This process (known as Jailbreaking) will allow the phone to work with any GSM carrier that supports SIM cards. This is the real trick to getting a good price for your phone. It'll increase demand and boost the amount of bids tremendously. You'll even open up the possibility of international bidders. The unlocking process is simple - run the QuickPwn software on your iPhone and it'll be unlocked in minutes. It's ridiculous how easy it is.
3.
Now that you've done the Jailbreak, it's time to sell on eBay. I would recommend a 5 day auction, a good picture of your phone, and the original box if you still have it. The real selling point is that it's unlocked, so make that clear in the listing. Any GSM carrier with SIM cards will work! This will also allow international bidders to use the phone, so consider shipping internationally to make the most money. It's likely that your phone will sell to someone from your country anyways, but the international bids really boost the end price. To help that exposure, also check the option to display your auction on international eBay sites.
4.
A lot of these things sell on eBay, so when you're setting up your auction it will be to your advantage to use some featured listing options. These can help your auction stand out from all the others. There's several types of featured listings, but the $10 option (to make your auction appear at the top of the search results) is probably good enough. You can add more options, but be aware that they increase the price. Use some strategy and save yourself money.
5.
Don't list anything but the bare minimum accessories with your phone. Include the cable to connect it to your computer and maybe the headphones. If you still have the original box, throw that in as well. Make sure to include it in the photos for the auction. Any other accessories you have (a dock, the wall charger, or even the headphones) can be sold separately in their own auctions. They won't sell for much, but every little bit helps.
6.
If you played your cards right, the auction will end at roughly the price of the latest model (the one you're hoping to buy). Experienced users who sell on eBay have even been able to get a high enough price to upgrade to a larger size. Check the completed listings to see what worked for them. If you have difficulty trying to sell on eBay, consider an alternative site like Craigslist. There you can post your phone for a high price and wait patiently for a buyer to come along paying cash.