Bus for a buck (or 20, but who's counting)

You've heard of the cheap Chinatown buses from Boston to New York. What would you say to a cheapie bus from Detroit to Chicago. Check out megabus.com, featured today in the Wall Street Journal. Prices are as cheap as $1.50 for certain cities in the Midwest. I checked a random trip from DET to CHI, and it said it was $20.