There are many factors to consider when installing an aerial.
There are probably 30 - 40 different combinations and therefore 30 - 40 different prices. Biggest is not always best. Contact your local installer more specific 'local knowledge' and an idea of the prices you can expect to pay at your location.
The CAI is the Trade Association for the Aerial and Satellite Industry, the 'CAI' does not install aerials or satellite equipment.