Well I had re3ad this somewhere, don't remember where, and copied it onto my computer ... tried it, and it actually works!
[1] Use a Save Sphere to get to the Airship, and go to Kilika Port.
[2] Go to the shop, just to the west and south of here the Airship leaves you.
[3] Purchase as many armors as you can carry for Tidus.
[4] Use a Save Sphere to get to the Airship, and go to the Calm Lands.
[5] Go to the Monster Arena, to the east of where the Airship leaves you.
[6] Fight Kottos, who drops 40 Healing Springs for an overkill.
[7] Customize [SOS Regen] on the armor you purchased from Kilika by using the
Healing Springs Kottos dropped.
[8] Sell the armor for a tidy profit (average 33,371 Gil per armor).
[9] Repeat.
Seems odd but it gets you tons of money.
Wings to Discovery,30 for Break HP Limit in armor, 50 for Triple AP in weapon
Shinryu drops them.
Or you can bribe them from Malboro in calm lads and chamber of the stolen fayth, or the Great Marlboro, Inside Sin, Omega Ruins
30 for getting 3 chests at chocobo racing
Winning Formula
30 for Triple Overdrive in weapon
Ultima Buster drops them in the monster arena Bribe from a Sand Worm in Sanubia Desert
99 for catching all areas