I paid a couple of hudred pounds a year or two back.
For that I got a mast, fixings and high gain ariel with a amplifier on the mast and high performance cable with the cable going in through a window ( no trunking inside needed)
Since then the working at height legislation has come in. I don't know if they'll insist on having scaffolding up for the job or whether they work under one of the exemptions.
Last time I needed scaffolding it was about �200 as well.
Probably varies by area, I'm in a rural area sort of Milton Keynes way