[jimbo2012]

The short answer is yes.

All add ons thru the builder carry a markup, say they quote you $2500 for something, it is billed perhaps with 20-40% margin of profit.

But you do get the warrentee behind it.

The trick is finding reliable contractors which this forum can help with recommendations.

Just don't give any upfront money, pay after work is complete and you are satisfied.