W-Item Cheat (Unlimited Items)
You can do this cheat after you’ve obtained W-Item Materia. Equip it to one of your characters and get into a battle. Make sure you’re battling a weak enemy to make this easier. Select the W-Item command on the character you equipped the Materia to.
Select an item that you can waste on a character (potions, ethers, anything will do). The menu will open allowing you to select the second item. Press Select on the item (don’t use it) and then Cancel the item selection. This will add that item to your inventory. Repeat this process until you have 99 of the item. This cheat only works on items you can select from the battle screen.
Turtle’s Paradise Bulletins
Around the world you can find bulletins posted about a bar opening called Turtle’s Paradise. Once you have read them all and talk to the restaurant owner he will give you a Power Source, Guard Source, Magic Source, Mind Source, Speed Source, Luck Source and Megalixir. Click on the link for information on collecting the flyers.
Ribbons are probably the most powerful and useful accessory in the game. Want a few more of them in your inventory? Make your way to the Northern Cave (Sephiroth’s Cave) and get into a battle with a Master Tonberry. He’s the little turtle guy who likes to stab your characters to instantly kill them and uses Everyone’s Grudge, probably the most annoying enemy move in the game. Equip Morph Materia and use the Morph command on Master Tonberry to transform him into a Ribbon.
Knights of the Round Materia
Quadra Magic Materia
HP <-> MP Materia
All of the above Materia are rewards of the Chocobo racing and breeding side quest. Click on the link for more information on how to get them.
The best and most efficient way to earn money in the game is to level and sell Mastered All Materias as you obtain them. It doesn’t require any sidetracking from the missions at hand, and every time an All is mastered you get a new one. The new one can’t be used as many times, but at late stages in the game it’s easy enough to get them leveled to level 2 or 3, which is almost as useful as the actual mastered All Materia. A Mastered All Materia sells for 1.4 million gil.