The going rate for Topre Realforce Numpads in the USA is $109.99 + shipping and tax. I found that Amazon.co.jp has the white ones in stock for approximately $93 including shipping. I just paid 10,497 JPY shipped, which at the time of purchase converted to $92.78. Here is the link:
http://amzn.asia/3qHSjal (note that not all listed merchants participate in the Amazon Global Shipping program; if the seller with the lowest price doesn't, it will tell you when you try to check out).
Edit: I should note, for those concerned about shipping time internationally, that Amazon uses an express service. Last time I did this (for a Filco wrist rest), it arrived next day to Los Angeles.
Edit 2: Pro tip -- select the option to pay amazon itself in JPY. Your credit card company will give you a better currency conversion rate than what Amazon offers. (Look for this choice near the price box during checkout).