On the heels of a BlackBerry launch yesterday, Boost Mobile announced the availability of its first-ever qwerty clamshell phone, the Sanyo Incognito by Kyocera. The phone will sell for $129.99.

The phone can be paired with Boost Mobile’s $50 Monthly Unlimited plan, which runs on Sprint’s 3G network and includes unlimited nationwide voice, text messaging and Web.

The Incognito features a glow-thru external display and a 2-megapixel camera with VGA camcorder and digital zoom. Additionally, the phone includes direct-to-text and camera keys, 2.6-inch internal display, music and video player, MicroSD exapandable up to 16GB, GPS and stereo Bluetooth.

Boost has been expanding its line-up of full-featured phones recently in an effort to dispel the notion that prepaid carriers suffer from a lack of diversity when it comes to devices.

“Consumers can expect to see a lot more from Boost in 2010 to meet the widening range of needs we’re seeing as we attract and target a larger group of customers,” said Neil Lindsay, chief marketing officer, Sprint Prepaid Group, in a statement. “Launching phones like the Sanyo Incognito with 3G capabilities proves that we are committed to the evolution of our brand, services and devices to appeal to a broader demographic mix.”