There's good news for anyone sick of their current cell phone: Resale markets are hopping, and you can probably sell it for about what you paid and maybe more! But there's also good news for anyone looking to buy a secondhand phone mid-contract: Resale markets are hopping and you can probably buy one for significantly less than you'd pay in the store.

This, experts say, is undeniably weird. Typically, a market is good for buyers, or it's good for sellers, but rarely both at the same time. But because people typically buy their cell phones at deep discounts -- i.e. a 16G iPhone on AT&T (T) costs $200 for anyone signing a new contract, $450 less than its full price -- it's possible to then sell that phone for more than it cost, yet still for substantially less than what a buyer would pay retail.

Another example: the Droid Incredible by HTC on Verizon (VZ) costs $100 for new contracts and $530 retail, and currently sells for an average $240 on eBay (EBAY) . That's a 140% profit for sellers and still a 55% discount for mid-contract buyers. "It is unusual," admits Alex Goldfayn, a consumer electronics expert who hosts the nationally syndicated radio show "The Technology Tailor Minute." It's a rare case of consumers' gadget-lust working out for all involved. "Any time you have enthusiasts for a technology, the resale market is very healthy," he says.

That sweet spot is due in part to the 12 million Americans who are expected to buy the Verizon iPhone this year, many of whom have started unloading their handsets. Although eBay listings for eight of the carrier's popular handsets collectively rose 24% in the week and a half after its Jan. 10 iPhone announcement, according to research firm Terapeak, prices (see chart below) dropped only 8% on average. (Because most listings run five to seven days, it's too early yet to tell which models will see significant price drops from the increased listings, says Tim Dubroy, a spokesman for Terapeak.)

International enthusiasm and demand has contributed to the wonky pricing vortex. "Despite the numbers [of handsets] we're getting, we're not getting enough to satisfy buyers," says Israel Ganot, the chief executive for electronics trade-in site Gazelle http://www.gazelle.com, which sells the thousands of iPhones it receives to wholesalers who in turn sell them to customers in China and other countries.

Although sellers are making the more obvious profit, buyers aren't getting a bad deal, either. As supply increases in coming weeks and some formerly-hot handsets age out of favor, resale prices are likely drop by another $30 for Android phones and another $60 for other smartphones, says Delly Tamer, the chief executive of LetsTalk. Even though the average Motorola Droid X is selling for $310 on eBay right now -- $110 more than the price for new contracts -- someone who needed to replace say, a damaged phone mid-contract would still save 46% compared with buying a new one directly from Verizon.

Even an old, out-of-contract smartphone can still be worth something on the resale market. They're prone to more fast drops as new, advanced smartphones enter the market, so it's better to unload them sooner rather than later, advises Gaton. There, though, the number of people unloading, say, a 2008-era BlackBerry Storm can have a positive impact. Gazelle's maximum price on that handset actually increased $8 since mid October, to $52.

Both buyers and sellers will benefit from shopping around at resale sites -- sellers to check prices, and buyers, to find out where such sites are reselling purchased items. Some of the best are Gazelle.com and NextWorth.com, which resell gadgets on eBay, Amazon and other sites as well as recycle them, but you can also fetch a good price on trade-ins from Toshiba, Radio Shack (RSH) and Best Buy (BBY) . Even the carriers have their own programs.

Whether buying or selling used cellphones, there are pitfalls. Sellers must take care to remove personal information they keep in a phone, from numbers and emails to photos and apps. There are plenty of free resources online that can walk you through it, like ReCellular and the major gadget publications, and many of the third-party services buying used gadgets will wipe them for you for free, Goldfayn says. Buyers should also peruse listings carefully for reports of damage, and use free online guides like those at Ehow.com and eBay to figure out how to check for less obvious problems, like interior water damage.

* Assuming all phones in good condition, with all needed accessories and minor wear.