Solved this issue. Apparently some accounts don't accept credit cards, and thefore can only accept Paypal tied to a bank account.
While I've seen sellers marked as Paypal Only, is there any indication for accounts with a No Credit restriction? I spent the better part of four hours attempting to sort this out with extremely unhelpful eBay account reps, and finally figured it out on my own. This was not helped by eBay's messaging censorship policies, which made it near impossible to communicate with the other party.
