If is see GBP, then I automatically add about 60% to the price. No big deal - it just requires you to be somewhat familiar with other currencies that are commonly used. The variance currently stays around 50% - 60% for the British pounds sterling.
By the same token, you don't see those add-ons that are advertised in USD displaying how much it cost the fine folks over in the UK to purchase, or how much it costs for the folks that use the Euro.