I'll get straight to the point and put you all out of your misery in terms of cooking recipes (which seemed to be the most common speculation:
So congratulations to those of you who guessed right. But the thinking doesn't end here - I'm sure some of you will want to rush to sell - don't just yet.
Some of these buffs are really nice but because of the speculation and stockpiling prices are generally falling. This is day one - wait for more peaks to come.
If you speculated on an item and don't see it here don't fret - there's more to discover. There's an artificing vendor in Lions Arch but I think that the fact it's only a chef and artificer to be conspicuous. It may be they're the only halloween recipe vendors or the others may be in other towns/cities.
We may even see some later. This event is running for a week after all.
And given that it's a week of discoveries we may see particular discoveries (new mystic forge recipes) that drive other prices up as we go on. If you have a material that fits in the forge during this event, don't give up hope (and sell at a considerable loss) if the materials you pick aren't in any recipes you can see today.
I also want to touch on the candy corn there. It's required for EVERYTHING. It's at about 59 copper now. I don't know how abundant it is yet but I DO know that these recipes - all halloween recipes - are available permanently but the ingredients (corn) might not be.
Candy Corn could be a great bet to stockpile - physically or by investment - for later months.
Now, off I go to find out more facts - share anything you spot in the comments below!