The OP's question was about booking BA fares using a VPN and my answer was tailored specifically to that. To look at the AA example, it still shouldn't matter where your VPN connection was terminated. The pricing from aa.com or americanairlines.co.uk would still be consistent. In other words if I am looking at fares on aa.com those fares should be the same irrespective of whether my VPN is connected to the USA, the UK, Germany etc. I agree that if you look at aa.com for an itinerary and then compare the price with AA's UK or German site you will see different availability and pricing. However, I always thought that you needed to have an address in that country in order to pay in that currency? For example, if I look at pricing a USA - UK trip on AA's UK site then the billing country's address defaults to United Kingdom and if I attempt to change it then I am redirected to aa.com and the itinerary is repriced.