It rather depends on Area and type of ariel needed, the going rate locally in Derbyshire for a standard Ariel without any special booster features, fitted to a normal sized house, is around £120. However, expect to pay more than this if you need a booster Ariel or your roof is extra high and difficult to access.
London and the southern areas tend to charge higher rates due to the increased wages and cost of living. Look on your local Trusted Trader website to find a decent reputable trader, and get a price quote before you allow them to start the work.
Is there such a thing as delicious ready meals?