All of the artists and mods can name a pet after one of the items needed, and the users have to find that pet in their pet groups. The first user to get all of them and send the links to you wins?
And of course, so it's not a mad hunt, each person will give a hint to which group it's located.
Example:
hint;
My pet has a thing for fairs!
I have a pet group called The Royal Faire, so it would be in there. They go and find it;

Pet's name: Trick or Treat Bag
They have to collect every one, and the first to send can win something. xD
Does that make sense?