Finding a seller with a sealed copy that ships international and is cool with taking the MSRP for a game that is essentially discontinued is going to be quite a task.
EDIT: Wait, you're talking about the lightgun peripheral, right? Not sure if that will be harder or easier to find than the game itself. How's it different than the NYKO gun adapter? Because that's pretty much everybody's "weapon of choice" so to speak.
Holy shit, just checked and this thing is expensive on eBay. Some people want $70-80 for it. Just get the NYKO Perfect Shot.