iPhone 4 trade-in offers promoted, some at $250

You can trade in your iPhone 4 for a pretty good chunk of change — enough, in some cases, to cover the likely cost of the new iPhone 5. But what you get for the old one will depend on where you do your trade, and of course, the condition of your phone.

Between now and Monday — the day before Apple announces the new iPhone — TheNextWorth says it is guaranteeing $250 for all AT&T iPhone 4s (16GB and 32GB). Traditionally, the least expensive iPhone 4 starts at $199, but that's with a two-year contract. The unsubsidized list price of a 16GB iPhone in the U.S. is $649 (from Apple), and it's even more expensive in other countries.

To qualify for the $250 trade-in, NextWorth says phones "must be in good working condition with no heavy scratches or cracks."

You can learn more at NextWorth's iPhone trade-in page. The company will lock in the price for 21 days.

Another site, Gazelle.com is offering good prices, too, with its standard 30-day price lock-in: $250 for a "flawless" AT&T iPhone 4 with 32 GB; $225 for a "flawless" AT&T 16 GB model. Verizon models of the iPhone 4 go for less — $201 for a "flawless" 32 GB model, and $180 for the 16 GB version.

A "flawless" phone, according to Gazelle, is one that has "no noticeable flaws, still in its package or looks like new," has "zero scratches" and has "no dust under the glass."

Why are the AT&T iPhone 4s getting top dollar over the Verizon versions?

Representatives from both sites say that's because the AT&T iPhone uses GSM technology, which is predominant worldwide, and best for re-selling the phones. Verizon uses CDMA technology, which is primarily used in the United States by Verizon and by Sprint. An unlocked AT&T iPhone could even be used in the U.S. on the T-Mobile network.

"The best time to trade an iPhone is between right now and the day the phone's announced," said Anthony Scarsella, Gazelle's "chief gadget officer. "Once the phone's announced, prices will start to drop a little."

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Another trade-in website to consider is BuyMyTronics.com.

Buyers appear to be eager for the new iPhone — when the next iPhone launches, it will have been about 16 months since the last one came out — and that may explain the trade-in fever Scarsella says his site has seen.

"Last year, we were getting 100 iPhone (trade-ins) a day pre-announcement of the new phone, and that spiked to 2,000 per day post-announcement," he said. "This year, we're looking at 700 trade-ins a day in the past few weeks, with a potential spike of 20,000 post-announcement."

On Tuesday, when Apple announced it would "talk iPhone" Oct. 4, "someone was trading an iPhone every 10 seconds," on Gazelle, he said.

"This behavior is very unprecedented," he said. "Gadget owners usually wait until the announcement (of a new device) itself, but this year because of all the rumors and hype, people are locking in their prices and trades early."

Related stories:

• Gizmodo runs fake 'world's first iPhone 5 review'
• Survey: 41 percent of mobile users to buy iPhone 5
• Apple to 'talk iPhone' on Oct. 4
• iPhone rumors: What to expect this October

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