Ratuken is sort of like the Japanese eBay. So sellers vary. Check the sellers reviews. Also go to the global site.
http://global.rakuten.com/en/ prices will be in USD and shipping will default to international.
Check out the sellers name on a watch forum like watchuseek if you are curious about others experiences with that particular seller.
Edit: wow I just checked the prices from watchcentre and boy are they marked up with the Aust tax. Eg the PRG270 that cost me around $110 is going for $369. And the PRG300 that cost me about $160 is going for $399