GameStop is the best place I know to get games online.

The Dawn of Souls version on PS is called FF Origins. You also want to pick up FF Anthologies and Chronicles. They have FF4,5,6 and Crono Trigger. So, If you do collect all the PS FF games you'll have 1,2,4,5,6,7,8,9,T. That leaves the yet to be released ff3, and the PS2 games FFX, X-2. And the GameCube game FF Crystal Chronicles, which many dislike but I find ok.