Computer-based OBD scanner roundup.
 

What's available and what's the best value for general automotive side-work, particularly Diesel pick-ups?

On eBay, it seems like there are a ton of $20 cables that just have a USB or serial connection on one end and an OBD port on the other, and then there are several free programs to do the interfacing.

Or I can buy an AutoEnginuity set-up with their cable and software for $150-250.

Or there are several other set-ups available for around $200 or less?