There are reasons not to buy directly from DJI, the most important is probably all the problems people have exchanging a defective one.
Better retailers will exchange a problem one for a new one. With DJI once you open the box your only recourse is to send it in for repair and be without your new toys for weeks.
You won't see any bargains until the next model comes out. Also DJI use's Fair Trade pricing with it's Dealers. In other words if a Dealer discounts the price he or she will no longer be a Dealer. Some Dealers may throw in an accessory or two. All in all you get a lot of product at the retail price.