I emailed our developer about an hour ago and asked him to reply to this thread. In the meantime, other members of the permies.com staff asked if I could say something.
I looked up the error code and it says
If the funding option selected by the buyer fails in a DoExpressCheckoutPayment or a DoAuthorization call, a funding failure recovery process is available to merchants. Error code 10486 is returned to merchants when a buyer's payment fails due to a bad funding method (typically an invalid or maxed out credit card).
I would test this out by buying these plans myself, but paypal won't let me buy from myself. :)
Anybody wanna try buying this or something from the digital market that is cheaper to see if it works for you?