Adrian, you're only half of a DIY....you at least have some decent training and know what you're doing. There are many people who have no clue, including some of the big box stores. There's a certain red big box store that sends people to me for steering wheel control interfaces all the time. They don't have the parts to do it, even if they have the ability. I don't understand why that is, but it's true.
I've always wondered about the "buddy" installs we all see....do all of these people have some idiot friend or is there just one guy named Buddy causing all kinds of chaos in the area?