Seven years ago when I lived in Portland I found a Haworth adjustable height desk at a place that sold used office equipment and furniture. It’s an older model of the newer Haworth desks and is spring-loaded instead of motorized. It’s very heavy, but I only paid $75. Was a great find; so much so that I’ve kept it through several moves. Hauling it up and down stairs is no fun, but worth it.
I definitely recommend adjustable height desks, as it’s helped me cope with RSI. The one thing I’d recommend to anyone looking for one, is make sure it goes high enough AND low enough. It’d be great if my Haworth went 2 inches lower. If it did I’d be able to sit with my knees and elbows at 90 degrees, feet flat on the floor. But it’s pretty darn close.
If I ever had to replace my current desk, I’d strongly consider something like the Lian-Li DK-05. I could re-build my desktop PC inside my desk (yes, inside) and free up space next to it. 