It's not Arden doing it so it doesn't cost anything.
If you buy a home theatre system through the big picture people, they install it for free. I paid a deposit to the Big Picture People a few months ago for the home theatre system. They'll come out and pre-wire at the frame stage.
When the house is complete you pay the remainder of the money for the system and they'll come and install it. They also do security cameras.
Just make sure you tell Arden and they'll note it on the contract to allow them onsite to do the pre-wire.