$500!? Plus shipping!? You can make a standing desk with $100 worth of Ikea parts then buy a tall stool/chair for $75 on Amazon. Bam, just beat your "most affordable" sit/stand desk by $325+. Oh, and you can have it next week instead of next year (or later).
I guess I'll start my Kickstarter campaign tonight.
P.S. 45" is not enough height for many of us tall folk, especially in dress shoes with a thick heel.