it depends what the signal is like to begin with m8, a 'standard' wideband aerial will be between ~£70-100 supplied and fitted, but if you live in an area where the reception is very weak then you could pay £250+ for a high gain aerial, masthead amplifier, power supply, brackets, pole for the extra height needed, the time to fit it all, and an expert with specialist equipment to alaign it all for the best possible signal