Now that Best Buy actually got in their FF X/X-2 shipments, they're confirming (in another thread since they locked that one) that preorders "should" get the upgrade...but are also saying that they received limited quantities of the special edition.
http://forums.bestbuy.com/t5/Gaming-Support/Final-Fantasy-X-X-2-HD-Remaster-for-PS-Vita/td-p/795342
What a mess, though. Nobody knew what was going on, there were all sorts of contradictions, etc. People were trying to get a straight answer from them for like half a year, and it seems like even they didn't know for sure until the boxes showed up at their stores. I wanted my 20% off, but in the end, I cancelled my preorder there and went to gamestop. Probably the safer bet, anyway, considering that when I picked up my South Park preorder, my Best Buy put all the preorder copies out on the floor. I was lucky to get my copy with the preorder bonus card before someone else snagged it.
So, yes, if you preordered from Best Buy, it sounds like quantities are limited, and, depending on how many people preordered at your store, you might want to get there as early as you can to make sure you get the special edition. Good luck to everyone!