best price for Assetto Corsa Competizione?

Just pick any one of the VPN extensions from the Firefox/Chrome stores. Most come with at least one server in all first and second world countries, plus the largest third-world ones. We are years past looking for proxy lists and messing around with the computer network settings.
As for which one… well, you need to experiment. It depends on where you are and where you want to pretend to be, so it is a bit of a guesswork, but at least most any extensions can be switched in a few clicks.