ekeller,
A couple years ago, I purchased at Walmart the Innova 3100a CanOBD2 code scanner between $90 and $100. It is very easy to use and provides some explanation with the error code. The scanner has a feature (it has green, yellow, and red lights on its interface) to indicate if your car will pass an emissions test. It also comes with a USB cable and software to hook up the scanner to your computer. I have never used the computer capability so I do not know the usefulness of this feature. This model is still available for sale at Walmart.
Dave