Got to jump in on this one. I think you are missing the perception factor. I've had perspective clients take my proposal for a complete network to a computer store to see if they could get a better deal. All the customer sees is a parts list. The computer store knocks off a few hundred bucks and wins the bid.
What they don't see is the experience it takes to make all of those parts work together, and get stuck with thousands of dollars worth of labor to fix the mess.
The average client is not going to see a difference between a $200 "ready to go store" and one that was tailored to their needs, until it's too late. The perception they get is that you are just jacking up the price. Once they think that, you've lost the chance to change it.
They can see the difference between selling tools and having someone build it for you. What is much harder to see is the difference between a product done by vendor A and vendor B. In that case the creator of the tools has an advantage of perceived experience and price.