Oh too true! Everyone should take some time to learn a little about their car, it would save them so much $$ in the long run.
CYF, rockauto.com is good. They usually have cheaper brands along with the factory, so it's up to you on how much you want to spend. Plenty of times you can get away with buying the cheaper kind, unless it's something like head gaskets. :D
You pull your own codes eh?
I log injector open time, air fuel ratio, spark duration, egt, and like 20 other things. Stand alone is the only way to go if you want total control.