I saw RHCP at the O2 in November and that was £60 in total, and I previously saw them in 2006 which was £40. Blame the economy as well as the lack of money bands make from CD sales these days. £55 ticket is the norm for 'big bands' these days.
Just remembered I saw Muse at the O2 Arena in I think 2010 and that was around £45/50 which wasn't too bad but it was so loud and I could barely distinguish certain things. May have been because I was near the front but this wasn't the case when I saw RHCP last year, was at the front for that too.