Trick or Treat!
This world event (Hallow´s End) is about collecting as much Süßes Saures as possible. We don’t care about the achievement, only about making profit with it.
Option 1: Pets
They are traded at 5.000 – 15.000 gold on the auction house. Prices are lower with the event coming to an end. So it is clever to start to sell them after 2-3 months.
Option 2: Achievement Die Maskerade
This achievement is about transforming other players with the wands you can get during the event. You can purchase them for 2x Süßes Saures from Stymie (Elwynn Forest) or Darla (Undercity).
With one wand you can transform five times. You need different wand for every transformation. That means you need 14 x Süßes Saures for 35 transformations.
Now let’s make gold with it! Very often you read something like “looking for transformation x, y, z. paying 200g per transformation!” in the trade chat. You can also offer your transformations directly: “Selling [The Maskerade] Achievement for 1k gold, /invite when interested”. You have to anticipate that you may get flamed (Who pays for that! Idiot..)
But there are many players that don’t care about gold and they will accept your offer. I once sold 7 transformations for 14.000 gold. But I get 100-200g per transformation on average.
How do you get your hands on Tricky Treats? There are different options!
You can finish the event “Headless Horseman” once a day and get 5-6x Süßes Saures which, considering the 15 days the event is going on, leads to 75-90.
There are enough daily quests to collect Tricky Treats aswell.
I prefer “Ein Eimer voller Süßigkeiten“. They are spread in the inns all around Azeroth and the entire World of Warcraft. For each finished quest you get 2-3x Süßes Saures and if you are lucky also wands for transformation.
As a bonus you get achievements and 7g per bucket. Head to http://www.wowhead.com/search?q=Tricks+and+Treats to see all the available locations for the achievements.