Very easy process.

Higuchi accepts cards or PayPal. I've used PayPal with him twice without any issue whatsoever, but he does have a secure card order form on the site. Click on the "How to Buy" link and follow the instructions. He always quotes and sells in Yen, which will be converted by your card company or PayPal. You loose a little in the conversion, but it's all part of the game. Good luck!