How can I make my android device think I am somewhere else in the world

I want my android device to think my phone is in The U.K so I can buy stuff in U.K pounds cheaper. I have set up my google wallet for the U.K. And sure enough the prices display in U.K pounds, I've installed Amazon underground and the prices in Amazon underground display in pounds, but when I download apps and open them the prices are still in U.S dollars. Or I have a "you are not eligible to purchase this app due to geographical restrictions". I have all gps location sharing off, using wifi, and my google wallet is set up to the U.K Any help out there?