$200 might not be that far off. $40/hour is a reasonable charge and an installer could easily kill that kind of time mounting the subs in the box, tearing up the carpet, making the wiring "pretty", putting the carpeting back together, and then adjusting the bass levels and providing the customer some hand-holding.
Not being a professional, I have easily killed entire Saturdays doing a sub install. It's been worth it to me, but I've found very few installs that were cookie-cutter and didn't eat up a ton of time until I got it just right.
I think if someone isn't willing/able to do the work themselves then they shouldn't complain when someone needs to earn a living doing the work. I personally enjoy figuring things out, but I've also messed things up a number of times!