Top 3 Tips to Get the Most Money for Your Used iPhone
Top 3 Tips to Get the Most Money for Your Used iPhone · Daily Ticker

As Apple (AAPL) gets ready to unveil its new iPhone model next month, plenty of fans are locked in two-year phone contracts and won't qualify for the $199 upgrade price. Unsubsidized iPhones sell for a lot more -- $649 for a basic 16 GB iPhone 5, for example. Apple is expected to announce its new models on Sept. 10, but they probably won't go on sale for a few weeks after that.

Related: Cellphone Upgrade Plan Winners: Customers or Carriers?

If you are not eligible for an upgrade but you just have to have that new phone, you can get back a lot of the purchase price by selling your old phone. And even if you do qualify for upgrade pricing, you can still unload your old phone. The trick is to move quickly and choose the right market to collect the most cash.

Where to Sell

Multiple sites exist that will quote a price upfront for your no-longer-cool gadget. Check a few boxes on a website, mail in your phone and then wait for your check. Gazelle.com may be the simplest -- they'll even send you a box to mail in your old phone free of charge. The site was offering $300 this week for a typical 16 GB iPhone 5 that was in good condition and ran on AT&T's network. Another site, uSell.com, was offering as much as $340.

If you're more comfortable selling things online yourself, and/or you want to raise even more cash, it pays to list a used phone on an auction site like eBay (EBAY). A iPhone 5 in good condition (AT&T, 16 GB) sells for around $500. After fees, a seller would gross around $450. But auctions can be unpredictable, especially if you don't have a positive rating from previous transactions on eBay. Some buyers stay away from new sellers, reducing the amount you might get for a phone.

Sites like Glyde are somewhere in the middle. They help you arrange a sale at a price you set and give pricing advice. For example, Gylyde suggests you list the aforementioned slightly used 16 GB iPhone at $426 (your take would be $385). You can set the price higher or lower, with the warning that higher prices sell slower and lower prices sell faster.

The worst bet is rebate offers for trade-ins from stores like Best Buy (BBY). The retailer was offering only a $200 gift card for an iPhone 5 this week.Obviously, prices will fall once the new iPhone is announced and people rush to dump their old phones.

The frenzy has already begun for this cycle. Gazelle says it has made 500,000 offers in the past seven days for iPhones -- a period of time after the Sept. 10 date leaked. That's almost double the number of offers requested in the prior seven days. The top models owners wanted to dump were the 16 GB iPhone 4S and the 16 GB iPhone 4, both on AT&T's (T) network, according to Gazelle.