Hmm standing desks have been the standard for office work in many years here in Denmark. You can buy them in any store that sells office equipment. Seems weird that would not be the case in the US. They usually cost from around $300 to $1000.
I especially liked having a standing desk, since I had severe RSI problems a few years before that. I managed to get rid of it, mostly thanks to using a break program, an ergonomic keyboard and a pen-like mouse, but being able to alternate between sitting and standing also helps. I've written more about my problems and how I got rid of them here: http://henrikwarne.com/2012/02/18/how-i-beat-rsi/