Go to Ikea. They Sell a really simple, yet really nice (and somewhat large) desk called the Jerker. I'm not kidding you. The Desk is called "Jerker". Anyways, I bought one for $79 bucks two years ago and I love it.
I got a desk very much like what you described from Walmart last fall for $20. The build quality isn't quite as good as my Ikea furniture, but it's not bad either. If you anticipate using it for a while, I'd go the Ikea route.-Ty