If you want to believe him, do so and buy raw materials. They rose quite a bit last double exp weekend.
God yah, it's so easy people are making bots for it based off the fact it's one of the most terrible grinds in MMO history.
Oh wait.
I like your signature.
As stated before, i don't believe it's necessary to show hostility over a simple tip. If you have any doubt about this keep it to yourself. I won't be stocking up on supplies just yet but ill be conscious of the plausibility closer to the date.
What were the main things, be specific, that were bought out last time?

