If you wanted a Leap Motion controller, you either need to buy the stand-alone sensor for $79, buy the HP Envy 17 Leap Motion Special Edition, or buy one of 11 other HP devices that came with a keyboard that have an embedded Leap Motion sensor. Now you can buy that keyboard as a stand-alone device for any computer for $99, Engadget was told at the Computex trade show. Of course, you’ll need to have the Leap Motion software installed, which can run on Windows 7 or 8 and Mac OS X 10.7 or higher. When Leap Motion was announced in 2012, we called it “one of the coolest pieces of technology we’ve seen in a while” and its gesture controls look like a vision of the future. Despite the initial excitement, though, it has struggled to attract strong developer attention.