OK, the cost of ingredients is one thing, but don't forget the extras:
Say you buy £150 worth of equipment and have to replace it every 5 years, and say you brew 500 pints per year. That works out at 6p per pint.
Then there's fuel. Say a 40 pint brew takes £3 worth of leccy. That works out at 7.5p per pint.
Then there's p&p on ordering your ingredients. Say that's £5 for every order and you place one order for every three 40 pint brews. That works out at 4.2p per pint.
Water isn't free. If you pay £1.50 per cubic metre, a pint will cost about 0.1p but you'll probably use anywhere up to 5 pints of water to make one pint of beer, so that's another 0.5p per pint.
So that's another 19p per pint in extras which almost doubles the cost based on ingredients alone.
Then there's your time.

Say you earn the national minimum wage of £5.80 per hour and a brew takes 5 hours plus (say) another hour and a half for cleaning, bottling, ordering, etc, etc. That's about another 94p per pint which totally dwarfs everything else. Of course, if you happen to be a doctor, lawyer or banker, you might have to add a couple of zeros to the wage bill.
So if ingredients cost 20p per pint, the total cost could be around £1.33 per pint and that's without paying for any tax, transport, premises, insurance, etc. Makes you wonder how the supermarkets can sell beer at the price they do. I guess it all comes down to the size of your mash tun.