I understand entirely, and to be honest I can understand how it can be hard for people to justify such big bucks on an install.
In all honesty for most people, it's probably not as much an issue. The only real issue for me is that like i said, I'm rediculously anal about sound! Before I begin any system, I spend countless hours, days or even weeks planning it out - choosing the right drivers, working out the best install locations, calculating the optimal crossover points, gain levels and angles, etc. When I do a system it's all about achieving the best possible sonic accuracy, and every single aspect is planned out 'to the T' to make sure I squeeze every ounce of potential out of it.
In a case like mine when you put this much time, thought and effort into planning, there is nothing more frustrating then handing it over to an install shop and finding they have got the angles wrong, got the sub volume a little off, etc. It was because of situations like this that in the end I ended up saying hell with it...only way to get it done how I want it is to learn the hands on stuff and do it myself.
Marty is a top installer though - I've spent a lot of time around his workshop and I've seen the amount of care he takes, and the quality of work he produces and his level of knowledge. I can talk to him about different configuration options, positions, acoustic theories, etc and he knows what I'm talking about - most installers get lost 10 minutes into the discussion and you just know they won't be able to pull it off.
Also he knows how infuriatingly picky I am and how much it means to me to have everything perfect - so I know if I ever did leave it with him, he'd make sure it's right.
Most people these days do pretty straightforward installs though (i.e. splits and a sub) so for most people it probably doesn't matter as much as it does for me. Setting up splits and a sub aren't hard for someone who has even half decent knowledge of audio, so most decent installers can pull it off well enough!