I suspect it is a lot like how long is a piece of string.
I was fortunate that I could get under the house to do the cabling and able to easily run the cable up the wall cavity. I suspect that in a brick house on a slab or a house where access is more challenging, the time and costs could be more.
Maybe get three quotes and see what they recommend in relation to the cable placement (within walls, in conduit on the external wall, behind the skirting board, office style whete conduit placed on top of skirting boards etc). I suspect running an external wall/skirting board conduit (external wall conduit has been installed on a house in our street) is the cheapest and easiest to install option for the cabling contractor , but may not be the most discrete one.
If one lives in a heritage residence or multi-unit complex, check to see if there are and restrictions to the placement of conduits, especially on external walls.
