For the viral popularity of stand up desks, the available products leave much to be desired. The general consensus in the comments is that a few of the offerings are great, but quite expensive for what they offer.
By my specs you get shelves/desktop 48" wide, where you have one 28" deep desktop, one 24" deep large shelf, one 14" deep display shelf, and two 12" deep accessory shelves. It's pretty modular, so you can configure however you like. It is nowhere near as adjustable as something like the geekdesk, but for about $300 you could build two...
I recently joined the crew of diy stand-up deskers with this: https://plus.google.com/105852617539894761688/posts/F4sN8nUd...
By my specs you get shelves/desktop 48" wide, where you have one 28" deep desktop, one 24" deep large shelf, one 14" deep display shelf, and two 12" deep accessory shelves. It's pretty modular, so you can configure however you like. It is nowhere near as adjustable as something like the geekdesk, but for about $300 you could build two...