darren said:
If you bring your kids with you for the day and fancy a drink buying 3 breakers for ?3 might smart a bit.
Why would it smart a bit?
Hidden Earth bar prices are extremely reasonable - I think it was ?2.50 a pint last year, so even if you only buy one pint plus a beaker, you'll pay ?3.50 (ie basically pub prices, and you'll have a souvenir beaker to take home). I don't know off the top of my head what they were charging for soft drinks, but my guess is that they were just as reasonable.
And don't forget that any profit from the HE bar goes back into caving good causes, instead of lining the pockets of the pub chain owner.