Without Skylanders at E3 this year, there has to be another E3 exclusive Toys-To-Life item, right?
But seriously, I don't think the character will be 100% exclusive to the convention.
I do think it will be at E3, but think as others have said, either the gold base is exclusive, or it's just a "timed exclusive" somehow.
Obviously LEGO loves their exclusives as anyone else, but can't see Supergirl be 100% exclusive to an event. LEGO isn't THAT crazy... right?