Lifehacker has a post about a reader, Matthew King, who took things into his own hands and created a standing desk workspace for himself. To accomplish this, he took the popular IKEA standing desk hack and modified it to suit his own needs.
You can see that he has both sitting and standing spaces at which to work, which is what I am also currently using. That way if you get tired, or want to eat while working, etc., you can sit down without going through the trouble of raising/lowering the desk, or going to another room. Great work on the wire tray under the desk to hold the cabling–looking good. Just goes to show you that you don’t necessarily need to spend $750 and up on a pre-constructed standing desk.