Looking for a simple button to place next to a product on external website so that buyers can pay via Amazon.
Amazon payments would be able to provide the service you are looking for.
Please have a look through the following help page:
[Amazon Payments account|https://payments.amazon.co.uk/].
In order for you to register for this service you will need to use a new e-mail address that is not associated with an Amazon account. This is because the service is not compatible with your existing account. If you use an e-mail address that is already associated with an Amazon account you will receive an error message.