RadioShack will put an Acer Aspire One 3G Netbook on sale Sunday for $99. But there's a catch. You also have to buy a two-year AT&T DataConnect contract.

The Acer Aspire One grabbed 38.3 percent of Netbook market share in the third quarter, propelling it past industry pioneer Asus and its Eee PC 4G.

Acer's Aspire One normally sells for about $300.

The RadioShack-AT&T offer, as previously reported, is valid through December 20. The 2.44-pound, 9.8-inch by 6.7-inch Netbook includes:

Built-in 3G capability
802.11b/g wireless (Wi-Fi)
8.9-inch LCD screen
Built-in Webcam
Intel Atom processor
Windows XP Home
1GB memory
160GB hard drive
Built-in memory card readers (dedicated SD and 5-in-1)

Other players in the Netbook market include Hewlett-Packard and Dell.