The store had its own online shop, which was somewhat cheaper without Rakuten Ichiba's commission.
https://kanteikyoku-web.jp/shop/products/detail/109497
Usually, if you want to buy from a store that does not ship outside Japan, you can use a proxy purchasing service like Buyee.
The price on eBay includes both the dealer's commission and the fee the dealer pays to eBay. However, buying on eBay allows you to rely on eBay's strong buyer protection in case of any issues.
If you use a proxy purchasing service, the total price you pay will likely be lower than on eBay. However, in the event of a problem, such as an initial defect, resolving the issue will be much more difficult.