Check it out: http://www.motor.com/MAGAZINE/Pdf/072002_07.pdf

It's a 7-page Acrobat file on how to choose a Scan Tool (mostly OBDII).

Their isn't much focus on the OBDI scanners in the article, i.e. TTS Datamaster isn't even mentioned, however the OBDII is covered in depth including manufactures, products, OS/hardware type, etc...

EASE seems to be the only Pocket PC compatible tool out there, while Palm users have 3 or 4 choices (unless you have a Sony Clie, only one choice there). Lists quite a few stand-alone hardware devices like Auto X-ray.

No prices listed, but it's a starting point for those needing OBDII scanners.