The salesperson will entice you with incentives, such as a cruise for two or 100,000 Marriott Rewards points. Be sure to put your own value on the incentives. The true value is likely to be around $1,500 - $2,500. That's a far cry from the $7,000 to $10,000 you can save by buying resale without incentives rather than paying $30,000+ to Marriott.

One more thing: Marriott doesn't usually negotiate on price. If the price is $30,000, that's the price. There is often a little room to increase the incentives, but not much.