You can use a credit card or send a personal check to the ISS treasurer. If you want to pay by check, it needs to be payable in US dollars and made out to "The International Symbiosis Society".  Mail it to the ISS Treasurer at the address below:

850 Insight Park Ave

Suite 223

University, MS 38677-1848, USA

Phone: +1-662-915-1731

e-mail: erik@fyhom.com