I have both bought and sold a number of items through Amazon Marketplace, but I would think long & hard about buying something as expensive as a large DLP through that channel.
The Amazon AtoZ guarantee only applies to non-delivery or misrepresentation of condition. And even then, it only covers up to $2500 including shipping. If the seller is not a Samsung authorized dealer (ie grey market), you may have difficultly getting any warranty coverage.
The old adage "if it sounds to good to be true..." probably applies here.