I got the one I'm using right now at Staples for around $120 (it's fairly stylish, well built, and big enough to keep my dual widescreeen 20" monitors that are hooked up to my G5, my big honking CRT that's hooked up to my PC, and still leave some space for basic desk-duties...needless to say, it's an L-shaped desk).
You may check around Staples.com to see if it's worth going in..I believe I got mine while it was on sale, so their stock may not always be quite as cheap as when I got mine.
If you have an Ikea nearby, that's probably your best bet. If not, don't pay their outrageous shipping charges.
I had their Jerker desks (had one "normal" and one "computer" version) and they are awesome. Very stable, good finish; should last a while.
Sold them when I moved (for almost what I paid for them mind you) and replaced them with a top and legs from Ikea (just whatever their standard top and round legs are). It works fine, but isn't nearly as stable as the Jerker desks (it also cost about half).