The device itself, with a two-year contract, carries a price tag of $179.99 in T-Mobile stores and online through T-Mobile. And while there have been rumors of the open source Linux handsets selling out in some markets, it still appears an ample supply is available.

Regardless, a search on eBay uncovered more than 500 listings for the device, in some instances commanding more than $400 in active auctions. A search of completed auctions found several T-Mobile G1s have sold from anywhere from $350 to $450. On Craigslist, another online market place, listings are asking anywhere from $400 to $600 for a G1.

Why are people shelling out so much?

It's likely that folks are looking to scoop up the coveted smart phone contract-free or without renewing their contract, planning to just pop in their SIM card and go. But since the device is carrier locked to T-Mobile, plunking down the extra dough likely won't result in drastic cost savings. To buy the device in-store or online through T-Mobile without a contract will run $399.99. With a two-year contract, however, the device costs $179.99 plus an $18 device upgrade fee.

Unlocked T-Mobile G1s, however, are selling in the $700 to $850 range. By unlocking the device, it will work on any carrier's network that uses a SIM card, such as AT&T. The unlocked device will not work on networks that do not support SIM cards, like Sprint Nextel and Verizon Wireless.

The G1's appearance on eBay follows a recent trend with devices, where sellers scoop up as many as they can and flip them for a profit on the popular online auction site.

When the Apple iPhone 3G was first released in July, similar auctions popped up, with the unlocked and jailbroken iPhones hitting $1,000.

The BlackBerry Bold 9000, the first 3G device from Research In Motion (RIM) Ltd., is also already available through eBay sellers weeks before the Bold hits U.S. stores on Nov. 4 starting at $299.99. Unlocked models of the Bold, which is exclusive to AT&T's network, are reaching as high as $800, with one locked AT&T-branded Bold topping $1,000 in a completed auction.

Online sellers are even looking to cash in on the BlackBerry Storm, the first touch screen BlackBerry, which likely won't be publicly available in the U.S. until the middle of November. A handful of pre-order auctions offer the Storm for more than $600, promising the Verizon Wireless exclusive device will be in stock on Nov. 10. Some Storms have already sold for around $650.