(Moving thread.)
I own a number of FF prints which I’ve purchased from a local store that specialises in anime and gaming merchandise (block mounted prints from FFVII and X, and a FFIX fabric wall scroll), but I also have quite a few posters I’ve aquired from various gaming magazines and publications over the years.
Most magazines advertise on the cover if they include posters, so keep an eye out at your local newstand or news agent, as you may get lucky and find one you’re looking for.