Any seller has a variety of restriction options available to them.
A seller can choose to block a bidder from being the winning bidder on any number of multiple items.
Specifically a seller can set it up so:
Can block "Buyers who may bid on several of my items and not pay for them"
Can "Block buyers who are currently winning or have bought XX (the XX being the choice of the seller) of my items in the last 10 days."
Can block based on feedback "Option to "Only apply this block to buyers who have a feedback score of XX or lower".
ebay states:
Consider selecting this requirement if you are selling expensive items and don't want to sell over a certain number to any single buyer. Learn more about how this requirement works.