Spyder,
This is a reply that I got from MTL_Runner on this very same subject (hope you don't mind, MTL!):
I like the Auterra because they do update the software very often and the portability just can't be beat. Using the PDA s a display and for running the software makes it much more powerful/flexible than any dedicated reader could be for anything close to that price (a snap-on reader can run $2500 to do the same thing!). Mark (Midiwall) also likes a unit that interfaces with his laptop and is cheaper ($90 I think?) but for me the added features of the Auterra (such as gear calculator, engine dyno, etc...) and the amazing portability (I don't like to lug around a bulky and delicate laptop in the shop or on a trip) make it worth the extra money.
I bought mine on eBay about 2 years ago now and I must say it would most likely be the most valuable tool in my toolbox. I got mine for like $180 but the auctions are always on there and if you are patient you can certainly get one in the $190-200 range. They are sold on there by auterra themselves so no worries on the warranty.
It has definately save me money. I bought it when I had my first check engine light come on in the 4runner (turned out to be an O2 sensor) but just to pull the code the dealer wanted $70! I said screw that and just put it towards the purchase......couldn't have made a smarter move. It is also awesome if you are looking to buy a used car. Just hook it up to any 1996 and later vehicle and there is no way someone can lie to you. It is actually quite intimidating for most and they will usually cough up any bad history on the car right away. You should see their jaws drop when you hook it up and pull the codes. If you know how to read the meters (O2 sensor voltage, MAF, etc) it can tell you exactly hw well the car is running or if something needs work. I have gone with friends several times to get a car and all were very happy and impressed.
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Hope that helps.
Bob