FWIW (and I have absolutely no personal interest in this) but I never buy any ticket for anything from anything other than an authorised outlet - this includes park tickets, concert tickets anything!!!

I can't imagine how disappointed (and humiliated) I would be if for any reason I was declined entry to the event or in this case one of the parks.

Even back in 1992 on our first visit to Orlando we avoided the ticket touts in booths (after all that is all they are) - they just smacked of taking a risk and to me it just wasn't worth taking.