Ecto's are way overpriced. Instead, buy level 68 rares as cheap as you can. They were about 22s each when I was on a few days ago. Then, salvage them either with Black Lion or Superior salvage kits. You get 0-3 ectos per rare. Repeat until 400, sell the rest for profit, or keep them for another craft.
Edit: typos. Dang tablet keyboard.