I have had one for several years. All of my vehicles are over 100k miles, and I do all my own service for the most part.

I highly recommend one if you work on your own vehicles. If you do, make sure that you get one that allows you to clear the codes once you've fixed the problem.

There are lots of different levels of readers, from very basic to very advanced. I would buy according to your level of expertise. No use having tons of functions if you don't know how to use them.

As you mentioned, pretty much any parts store will read codes for you if you don't want to buy a reader. My reader is an Innova, although I don't remember which model. I think it ran me around $100. You will save a lot more than that by not taking it to a mechanic.

Greg