You can make a stand-up desk from an old door and two sawhorses, customize a store-bought desk, or pay a company for a ready-made one. Here are some options:
Here are three examples of DIY options for making a stand-up desk: a sawhorse desk, a metal cart desk, and a plywood desk. If you are a serious woodworker, you can buy plans for a stand-up desk at Woodware Designs.
Ready-made stand-up desks
The Fredrik desk from IKEA can be put together to make a stand-up desk. IKEA also sells office table tops in various sizes and shapes to which you can add adjustable legs that telescope up to 42 inches.
Companies that specialize in stand-up desks include Geek Desk, Stand-Up Desk Company, Standupdesks.com, UpStandingDesk, and Beyond the Office Door.
If you like your office setup but want to add stand-up capability without adding more furniture, the Anderlyn Desk is a platform that sits atop a standard desk, creating a stand-up work surface.