Those sorts of brand names to come up through liquidations from time to time, but the thing with liquidated products is they are there for a reason. There are numerous reasons, including damaged, customer return and so on, but the big one is slow moving stock being cleared.
When you are talking about big brand names, you are talking about popular brand names, and that type of stock usually walks of a shelf and never see's the inside of a surplus supplier's warehouse because of that.
When you do see them on eBay at crazy prices, you could well be looking at anything form a fake, to a wholesaler selling direct or even a seller buying in super large loads direct from a liquidator.
eBay is seriously big business for a lot of sellers now, and that brings seriously big competition that drives prices to rock bottom.