After bluprntguy is hung for blasphemy, they will string me up too. I use the API master test kit. AND it's many many years old. Currently, I only test for nitrates, and my nitrates are so bad that I don't go for precision, I go for "is it less dark red than it was before?" At the moment, I'm only testing to see if it is going down, not what the actual number is.
I actually don't bother testing the other stuff much.
A few years ago, I did send a water sample away to get tested. It's expensive, but in one fell swoop it helped me diagnose my water problems (My Nitrates were over 200 ppm, when ideally it should be 0-5).
V