As known within SEO, it can make a difference (serps) if your targetting a country, UK for example then you would buy a .co.uk and it can be beneficial to use UK located servers. But does it matter in any way at all when your marketing through PPC? would you target a UK audience while affiliate marketing with a .co.uk domain but on a US/AUS/CA etc server. Obviously if someone is marketing with SEO and PPC combined in mind for a site then they would go for a server located at the country they are targetting, at least for the SEO reasons. But if only marketing with PPC, then not neccessary?
for PPC it does not matter where the server location is my server is in the US and i target Canada and the UK no problem