Buyers have 24 hours to settle their invoice. After 24 hours, sellers will have the option to cancel the transaction. Sellers may wish to contact the buyer first prior to canceling.
If payment isn't made within the required time-frame, the seller has option to:
Cancel the transaction by visiting their Items page and clicking Mark as Canceled under the menu next to the Unpaid item. Buyers with multiple cancellations will lose ability to bid on items.
Leave the buyer negative feedback. Buyers that receive negative feedback from a seller will be blocked from buying from that seller again. This option should be used with care.