The power switch was only ever available on JDM cars, so most of the world will be using the same parts references that you are.
In other words no English speaking market or European market will have parts reference for this particular piece of kit. If you want to buy a Japanese switch to fit your car you will need help from somebody in Japan who has access to the dealer network and can look up the part number for you.
Your best bet to get one second hand will be to get one from a scrapped [you guys call that totalled, maybe?] JDM market car. This will not be easy for you as US regulations prohibit the importation of JDM SVXes. You'll have to find a scrapped one in England or Japan.
Your next possibility would be to get one from a front cut of an SVX that came from Japan. There is an outfit on eBay called EnginesUS. They import engines from scrapped cars in Japan. They are worth a call, but may not be able to help because they import the bare engines and gearboxes which are stripped for them in Japan.
A better bet is to keep an eye to the eBay shop of RPM Garage.
RPM
Their prices seem reasonable and they pull a lot of parts.
You might also keep an eye to Australia and New Zealand. There is at least one guy breaks Japanese SVXes in New Zealand. Japanese SVXes are much more common in NZ than in Australia because of import regs.
Your options are:
eBay
England: scrap yard breaking Japanese SVXes
Japan: scrap yard breaking Japanese SVXes
New Zealand: scrap yard breaking Japanese SVXes
Australia: scrap yard importing Japanese SVX front cuts.
You will need to run Google searches and eBay searches to contact these people. Japanese SVXes are now getting rare. There is no easy way.
Hope that helps
Joe