>In the UK, swap dollars for pounds, such is Apple's magical currency conversion rate
Otherwise known as the actual currency conversion rate.
The monthly average exchange rate between GBP and USD for the last six months ranges between a high of 1.28 and a depressing low of 1.21. Factor in that we are required to include 20% VAT in the headline price and this represents a markup of somewhere between 0.83% and 6%. Given the ludicrous instability in the pound in these days of Brexit-induced insanity, I'm frankly astonished the markup is that low.