Your old iPhone could be worth big bucks. Here's what to look for

(NEXSTAR) – The newest iPhone models are currently available for preorder, but it’s the older ones you might really want.

With Gen Xers and Millennials now beginning to feel pangs of nostalgia for the technology of their younger years, some technophiles are willing to pay big bucks for your earlier iDevices.

“The rarity, scarcity, and the collectability of these pieces, it’s just becoming nostalgic with the 40-to-50-year-old group of consumers,” Bobby Eaton, of RR Auctions in New Hampshire, told Nexstar.

Eaton is talking mostly about iPhones. In recent years, RR Auctions has facilitated the sale of numerous first-generation iPhones, one of which went for over $147,000 in March. Last year, another rare specimen went on the auction block at LCG Auctions in Louisiana, where it sold for a record $190,373.

"As we all know, the iPhone change the world," Eaton told Nexstar. "So in the last three years, iPhones — specifically sealed iPhones — are going up in value depending on what model they are."

But collectors aren’t looking for just any old iPhone. Much like video games and VHS tapes, the phones selling for the highest prices are factory sealed, and in mint condition. And right now, only certain models are coveted by collectors — namely, the first-generation 4 GB and 8 GB models which debuted in 2007, including the 8 GB model with an iTunes logo on the cover of the box.

“Besides the first-generation products, the market drastically changes,” Eaton said. “There’s not that collectability yet for [later] models.”

The most valuable iPhone of the three mentioned above — far and away — is the 4 GB model, which was discontinued when Apple dropped the price of the 8 GB version only two months after the 4 GB version's debut. (The big sellers mentioned above were both 4 GB models.) But the 8 GB models fetch a pretty penny too, especially if it’s the earlier version, before an image of the iTunes app was added to the product photo on the outside of the box.

Opened first-generation iPhones might even be worth a few thousand, but they need to be in mint condition, according to Eaton. If they show signs of use or damage, they’re basically worth “nothing” to a collector, he said.

Other than iPhones, first-generation iPods and iPads are also quite valuable to collectors, but, again, only if they’re in great condition, and preferably sealed.

But what if you’re in possession of another phone brand, like a Samsung or an Android? Sorry, but the value of early models is “not even close” to what an Apple enthusiast would pay for an iPhone, according to Eaton.

“Probably the only comparable thing that we’ve sold to the iPhone is … an early Motorola flip phone that was sealed in the box,” Eaton said. “And it sold for $250.”

Still think you’re sitting on an iGoldmine? If you happen to have a more valuable sealed iPhone specimen, first check the serial numbers and IMEI numbers on the box to confirm it was never activated. (Fraudsters have been known to shrink-wrap used iPhones and pass them off as factory-sealed, Eaton explained.) You can try and get it graded by a grading service, too, but Eaton said you could just submit photos straight to auction houses that specialize in vintage technology, to hear their thoughts.

You might want to do that sooner than later, too. While Eaton doesn’t believe interest is waning, he can’t predict how much collectors in the coming years will be willing to pay for early iPhones, iPods and iPads.

“If something is super rare, there’s going to always be a market for it,” Eaton said. “It might not be the prices we’re getting now, but they’re going to have substantial value.”