How much should I budget for TV install?

[Easty-5]

We have bought a new build house that will be ready April 2015. I am starting to work out how much we need to budget for everything and I have a price for everything other than our TV installation. I will be looking for the following;

1. A 50-55" TV mounted on our living room wall with Sky+HD & soundbar. We would also maybe like a socket with HDMI connections down near the bottom corner of the wall for temporary connections.
2. A ~32" TV mounted on our bedroom wall with Sky+HD Multiroom.
3. A ~40" TV Mounted on the wall in Bedroom 3 with a Sky Magic eye or the equivalent. A socket with HDMi connects near the bottom of the wall so I can connect my XBox One.

I will be having additional sky points put in the rooms and a double socket in the middle of each wall. Is there anything else I can have the developer do to make life easier for the guys installing my TVs. Running the HDMi cables behind the wall is out of the question. They wanted £605 per room to run 3 cables!

Also, does anybody have a rough estimate at how much I should look at budgeting for just the installation, not the cost of TVs & Soundbar? I am in North East Scotland if that makes any difference.

[henrycrun]

Only need one TV.
Bedrooms are only for sex, reading and sleeping.

[megaphone]

If you can't get the relevant cables in the wall then you need to have some sort of conduit put in so you can pull cables later, needs to run from the TV position to the point where your Skybox will go. Needs to be big enough to allow a HDMI connector and cable to pull through easily + other cables.

You should also consider, aerial/Freeview to every point, 2x ethernet cat5/6 to every point.

Will the builder allow you to employ an AV installer whilst works are still in progress?