I've used standup desks for over 30 years.
First drafting tables. With a drafting stool to switch between standing and sitting.
Then cubicle desks modified to permanently stand up.
I found myself alternating between standing and squatting in my chair.
Then the motorized digital kind with the preset push buttons to set the height.
I really liked those. I could stand 90% of the day and then effortlessly sit when it seemed like the thing to do.
So... having the ability to switch between stand and sit is the way to go.
The cheapest method would be a standing desk with a drafting chair.
The fastest/easiest method is a motorized desk.
But... If I were ever to own a home and buy a desk again, I would buy this one:
http://ohiodesign.com/product/adler-table/
I just love the design. Simple. Iron. Wood. A machinist's wheel.
Not likely to happen though.
Mostly what I do these days is set the chair on the desk and the notebook on the chair. That is usually a workable height whenever I am in a hotel or rental. The aesthetics suck, though.