About to beat the game...some help? [Maybe Spoilers]

[ChocoKid21]

Alright, I'm about to venture into the last dungeon and here's my stats.

Vaan - 44 - Melee (Sword & Shield)
Balthier - 43 - Ranged (Gun)
Fran - 42 - Ranged (Bow)
Basch - 41 - Melee (Axe & Shield)
Ashe - 41 - White mage (Pole)
Penelo - 41 - White mage (Rod)

I almost have the entire top of my license board filled (minus the espers and some accessories) for every character.


Espers
Belias (Basch)
Mateus (Vaan)
Adrammelech (Balthier)
Shemhazai (Fran)
Hashmal (Penelo)
Famfrit (Ashe)


Where can I buy Ethers? (If possible)


Oh.....do I need to be scared about the final boss? (I won't name it, but I know what it is).

The strategy guide says that its an extremely hard battle but they also said the past 8 boss fights were really hard and my average time in beating each boss was about 3 minutes....