If you don't wish to pay an annual lump sum and don't have a US bank account (I don't as I live in UK and don't want one) you can spread the cost by making advance payments.
To do this select 'Pay by contract' in the annual dues payment screen, then click 'pay other amount' and put in how much you want to pay. Don't worry that the balance is nil.
Select your card, submit payment, and you get a pop up saying total amount exceeds dues balance. Click submit payment again and it's added to a credit 'The overpayment will remain in the account as a credit balance, and will be applied to next year's dues'.
This way I'm always in credit, and when January comes I'm not paying a couple of grand in dues.
I obviously lose a bit of interest on the money, but it's hardly anything.