As far as I know Rakuten Global is down, which means that Kobudo and Americaya are not able to process international orders through Rakuten.
Before they went down, their prices normalized with other Winning sites, so there was no longer a cost benefit for using them.
The 3 options left (as far as I know) are:
http://www.winning-usa.com/ (for people in the United States)
https://www.kozuji.com/ (legit store, prices are okay less than 18oz)
https://www.wjapanboxing.com/ (the official store)
These are organized from least expensive to most expensive.
Before Rakuten Global went down Americaya was no longer cheaper than Winning USA store anyway and shipping times were longer.