~Buy every sphere at the Luca Theater~

This trophy is pricey as it requires you to spend 426,000 Gil and is obtainable once you reach the final dungeon of the game; this is because you have music and movie spheres, and movie spheres can only be bought once you see the FMV they pertain to. Once you have access to the final dungeon, return to Luca and enter the theater; it's the path heading north when walking away from the stadium area. Once there you can talk to the two short NPC's standing around; the one on the right sells movie spheres and the one on the left sells music spheres.

You need to buy all 50 movie spheres (at 5,000 gil a piece) from the attendant on the right. You also need to buy 68 music spheres (at 2,000 gil a piece) from the attendant on the left. With this you may notice the trophy doesn't appear. After buying all the music spheres, talk to the attendant again and he'll sell you 3 more spheres for 40,000 gil. Once you have all 50 movie spheres and 71 music spheres you'll earn this trophy. If you don't want to lose all that gil, save your game, get the trophy then reload your save.