Save Up to $175 on iPhone at RadioShack

Is an iPhone 4 (s aapl) on your holiday wish list? If yes, RadioShack has an attractive deal starting Saturday, Dec. 4. You instantly save $50 on the iPhone 4 and 3GS, but with trade-ins on your old device, that could climb as high as $175.

The deal, which RadioShack made us aware of via email, only lasts until next Saturday, Dec. 11, so you don’t have much time to make up your mind, but it’s not a bad deal even considering that the iPhone is already halfway through its upgrade cycle. Because it’s so much easier than writing it out, here’s what The Shack is offering in convenient table form:

There are, as you might expect, a few caveats. Phones obviously have to be purchased on a new two-year contract with AT&T (s t), and that means you have to either be a new customer or eligible for upgrade pricing. For the trade-in to apply, your old phone has to be in pretty much pristine working and cosmetic condition. You can see if your old iPhone qualifies either at your nearest RadioShack store, or using the company’s online appraisal tool.

Speaking of that trade-in, you’re probably better off trying to sell your old device on eBay or craigslist first. That $125 discount on the 3GS could translate into around $300 in your pocket if you sell the device second-hand yourself, which would make the iPhone 4 basically free (barring applicable taxes) with the automatic $50 discount.

A $50 discount may not seem like much when you’re spending nearly $300 anyways, but it’s likely the steepest price cut you’ll see on the iPhone 4 this holiday. If you’d rather not wait for the iPhone 5, and you’re eligible for upgrade, it’s not going to get much better than this.

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