Defeat Mimics in Omega Dungeon with Godhand (mercury crest & sigil combined) to get 100k gil, and defeat many One-Eyes in one battle in order to get 3-slot weapons with Triple AP, it sell for 67k gil, or defeat Thu'Ban to get 4-slot weapons with Triple AP & Triple Overdrive that sell 220k gil... this should help you a lot. Bribing Malboro for 540k Gil to get 4 wings to discovery, getting 80 WOD costs 10800000 Gil for bribing 20 Malboros, what an expense. D: