I've seen quite a few others, but I think the special item find is the one that most people will want in the long run, because it increases chances of cards, heros, costumes, etc.

Are they worth anything?

Seems kinda a low roll on the core I have a 22% Special Item Find Core and a friend of mine has a 28%. But yeah im sure they will be worth something to someone that really wants to stack it.

Ooooo. I didn't know it went higher then 12. Thanks for this, now I'ma be on the look out for a 30%+ one:P

I have found 2 of these and 1 rarity boost one. I think they are probably common

I honestly dont know how high they get bud we'll have to see in due time.