Have a search of the forum cos there are quite a few posts, and there was one a while back where everyone posted what they spent on gear, so that should give you a good idea…
As for helmets and 80 quid helmet (so long as it has all the right stickers) will give pretty much as good protection as a 180 pound one, the extra money goes on making the helmet more comfortable, better vented, replacement inner linings, paintwork like your favourite racer and sometimes reducing wind noise. A more well-fitted £80 helmet is more safer than an ill-fitting £180 one so try as many as you can in your price range in a shop where people are friendly and can adviseand get the one that fits the best.