I built one out of parts from Ikea recently. Cost $70 CAD, probably much cheaper in USD. http://iamnotaprogrammer.com/Ikea-St...2-dollars.html

Standing in one place for long periods of time is not easy on your body. After about 4 hours, my feet hurt so bad I have to sit down. I got a high barstool that I can pull up and sit in and still reach my keyboard. Also a gel pad to stand on. Carpet wasn't cutting it.