Welcome to the forum! Do you mind if I ask how you got into your career? The auto mechanic I take my car to for its yearly government regulated inspection does the basics cheap, but it's very much a get-what-you-pay-for kind of deal (which is what I usually prefer in mechanics), but I learned the hard way that he's not too adept at the electronics side of things.
Seems to me that your field would take a fair bit of training beyond being just a guy who likes to mess around with cars?