For the speed of its march toward becoming the country s largest public company, Apple (AAPL) has its gadget-happy consumers to thank -- particularly the devotees willing to stand in line for every new version of the iPhone or iPad. But those technophile consumers aren t just the Pavlovian spenders they might at first appear to be. Apple products hold their value much longer than other consumer electronics, says Toan Tran, an equity analyst who covers Apple for Morningstar which means reselling an old Apple device can be a smart way to fund a new one.

For example, an AT&T (T) customer who bought an iPhone in 2008 for $199 could sell it today for as much as $104 on trade-in site Gazelle. That s enough to cover more than half the $199 subsidized price of the newest model. In contrast, a BlackBerry Storm, which cost $199 in 2008, would now fetch $44 at most. For an older 13 MacBook, Radio Shack (RSH) will pay as much as $315, which covers almost a third of the $999 price tag on the newest 13 model. And even a battered Apple device isn't worthless. BuyMyTronics.com will pay $35 for a broken iPad with extreme damage and no charger.

Apple prices hold up largely because of good engineering and high demand, says Tran. And, there s Apple s name-brand recognition and loyalty. The company also doesn t make very dramatic changes from generation to generation, says Andrew Eisner, the director of content for marketplace Retrevo. Current software and many apps still work on older models, and similar ports allow interchangeable use with chargers, stereos and other accessories. Considering that Apple allows few discounts, a slight break on relatively new technology can be a good deal for buyers, he says.

To sell an old Apple device quickly and with minimal hassle, try a trade-in site, says Natali Del Conte, a senior editor at CNET. Gazelle, Toshiba, Radio Shack and Costco will all give free estimates of resale value. Putting up items on eBay is riskier and potentially more rewarding. International bidders and Americans looking to buy a newer iPhone before they qualify for the carrier s lower subsidized price ($199 versus $599 for a 16GB phone) bid up prices as high as $1,000. But don t expect such a windfall. According to bid-tracker Honesty.com, a buyer shouldn t pay more than $180 for an iPhone that s two generations old.

To maximize the value of an Apple resale, don t wait too long, experts advise. Prices will drop as soon as there s something newer on the horizon, Eisner says. If you don t already, pay attention to Apple s scheduled product announcements and rumors about what new items are likely to be introduced, and when. While the third-generation 32GB iPod Touch was the newest out there, a second-generation model sold for as much as $93 on Gazelle. But after the new fourth-generation was announced Sept. 1, the maximum offer dropped to $75.