Payment methods to accept. Online checkout methods are 'checkout_ach' and 'checkout_credit_card'; offline methods are 'ach' (manual bank transfer) and 'check'. If you omit any checkout_* method, both online methods are enabled by default. To offer only one online method, pass just that value (e.g. ['checkout_credit_card']). Add 'ach' or 'check' to also accept manually-recorded offline payments.