Ahh... Toronto. Get a flahlight and shine it where the book said it should be... there is a cover there and you just have to flip it open to reveal the plug. For MB, they are under the steering column area.
The Auterra is pretty nice... I set up my friend with one for his Palm long time ago. It was a simple code readout and it will tell you what that code means when you click on it. As years go by, Auterra upgraded their software to include dyno and some other goodies.
MB specific scanner are very expensive and unnecessary for most DIYers... I believe their products starts at $700 and goes up to $11,000. Most is around $4000 range.
Forget about ebay software scanners... I got one.... It does read MB specific informations but very limited in other ways that I wanted.... it is basically a working stripped down old software of Carsoft... illegal copy with zero instruction, zero instruction and zero support.