I know the internet is worldwide but I'm in the U.S. so this is U.S. based. 9 months from the release of X and we still have no Diance news not to mention those other 2 legendaries for X & Y. Unless you kept up to the T with EVENT legendaries you are out of luck! I understand not keeping up with games buy them used or in the case of the OR/AS remakes that is where I'm getting the Gen 3 legendaries (and hopefully some other legendaries that are added into it.)
I got a Mew back in the R/B era from a Pokemon Tour thingy but dropped out of the series until Black and didn't get Black 2 so didn't get the Gen V EVENTS (Did you have to have B/W 2 ONLY? I was confused on that part so never got Genescect Melotta etc.) I can get to a Toysrus and Gamestop locally fine just they release them so sparingly it's crazy. How about an EVENT Legend a month that about covers them all.
Do you give up on the EVENTS and completing your Pokedex? It may be years before they all get rereleased again. If you miss an EVENT item/pokemon you are OUT OF LUCK SORRY!