Where can I get an Ofuda representative of Inari?
In Japan, any staffed Inari shrine. Outside of Japan, you can order one from Shusse Inari Shrine of America (a bunsha of Shusse Inari Jinja in Matsue): http://shusseinarishrine.org/?goods_category=ofuda
They ship internationally.
Really the only incorrect answer is “eBay/Rakuten/etc”