I am not sure what you mean by WM but I personally would not buy tickets for any of the parks in Orlando except through the parks. There are a lot of people here who sell bogus tickets.
I live in Orlando now and there are constantly stings going on here because of all the illegal tickets being sold through some of these stands and such.
I will also suggest that if you plan on going to Harry Potter at IOA that you plan on waiting. Park opens early for hotel guests to get in so there are always people waiting. I have found that later in the day it is easier to get into the area.
Good Luck!!