koen - 10:45 pm on Jul 31, 2010 (gmt 0)
Thanks for keeping with me.
I was following the product advertising API. Under the section 'How Do I Make Money Using the Product Advertising API?' it reads 'You need to get an Amazon Associates account and [text left out]. For more information about getting an Amazon Associates account, see Becoming an Associate [=link].' This link leads to the affiliate program page. There's also a guide with same name and layout but a different version that says 'To become an Associate 1. Register with Amazon Payments at ' leading to a link where it says I need a US based visa card.
I'll try the first version (without visa) and see how far I get.