The whole Dragon Dash set are given as reward of the new event Dragon Dash in Guild Wars 2 now.
Want to get the whole Dragon Dash sets? Then you may join in the game and to finish the content so as to get them or you may also purchase these weapons from the black lion trading company by spending some Guild Wars 2 gold .
Horns of the Dragon
Holographic Dragon Wings
Holographic Shattered Dragon Wings
Dragon's Jade Weapon Skins
Helmed Moa Racer Mini
Pay attention that there are not available before June 11th, and all of them are not released at the same time, so if you want to buy the whole set, you may need to wait for some days.