If you decide to take the leap and open your auctions to an international audience, you need to be prepared for a new world of activities no pun intended. Selling outside the United States especially the shipping part of the processis much different from selling to someone in New York or California.
One of the issues with selling outside the United States is in dealing with foreign currency. First, you have to convert it to U.S. dollars. (How many lira to the dollar today?) Then you have to receive it in a form that is both secure and trusted. (Do you trust a personal check drawn on a small Spanish bank?) Then you have to find a way to deposit those fundsand convert them to U.S. dollars. (Does your bank handle foreign deposits?)