If you would like to be upgraded now, then go ahead and upgrade, and then send us a manual payment for the difference by logging into your Paypal account and clicking the “Send Money” tab at the top. Payments can be sent to firstname.lastname@example.org. In the notes, please let us know that this is a prorated amount for your upgrade. We will then go ahead and manually upgrade your account. This step is unnecessary if you are paying for your account with a credit card.
Paypal should handle the conversion for you if you specify that you need to pay in American dollars.