Here's a quick e-commerce lesson for you: Don't validate credit card transactions based on IP address location.
I left the internet fax provider I've had since 2003 because they wouldn't let me pay them.
I wasted an embarrassingly long time trying to find a cheap/free way mask my IP address. I eventually gave up trying to give them money.
I Googled, read a few quick reviews, and found a new, better provider in 5 minutes.
Lots of customers travel or live outside of their home country.
Don't make it difficult (or impossible) for them to pay you.