http://www.ikea.com/us/en/catalog/products/90087541/
And pair it with a bar stool. I've done just that and it's got me standing more often than the 5x more expensive adjustable solution would have done. That's assuming the default position for the adjustable would have been down. Which it would have been for me. It's sturdy, compact and tidy when coupled with the under-desk cable-tidy (just fits diagonally).
I've lost the comfort factor of the big chair and desk, but I've gained a more active default position. It's also easier to wham the treadmill under the desk when I'm feeling lively.
Folks, I do try not to be a tragic startup cliché.
http://www.ikea.com/us/en/catalog/categories/departments/bed...
While its not really designed to be a standup desk, it works quite well for me. I only use it for a couple of hours or so a day though.
It is certainly good value, and a fraction of the price of the one I had for work a few years ago (different brand totally). It can feel a little flimsy/wobbly when raised, but certainly not dangerously so.
http://www.varidesk.com/standing-desk-pro-plus-36
Best of both worlds.