~Wowwiki: Base Mana~
The term "Base Mana" refers to how much mana your character has before it is modified by Talents, Intellect, Enchants and other item effects. Quite a few spells require a percentage of your base mana to be cast, including all Warlock pet summons, Druid shapeshifting spells, Misdirection, Resurrection and Blink (in 2.4) spells.

The value is dependent on class only, not on race.

Base mana values at level 80
These are the correct values as of Build 8926 of the 3.0.2 Beta/PTR

Class Base mana value
Druid 3796
Hunter 5046
Mage 3268
Paladin 4394
Priest 3863
Shaman 4396
Warlock 4294

Druids still beat priest, but at least paladins and shamans are 4390ish.

For a level 70 character:

* Every class except Warlocks uses: (Intellect/80) + (Spell Critical Strike Rating/22.08) + Class Specific Constant
* Warlocks use : (Intellect/82) + (Spell Critical Strike Rating/22.08) + Class Specific Constant
* Class Specific Constants:
o Druid - 1.85
o Hunter - 3.6
o Mage - 0.91
o Paladin - 3.336
o Priest - 1.24
o Shaman - 2.2
o Warlock - 1.701
o Rogues and Warriors have a spell critical strike chance of 0% no matter what their Intellect is. However, the Warrior ability Thunder Clap uses Spell Critical Strike Rating to determine the chance to crit. Rogue poisons use this and Spell Damage as well.

priest are dead last for healers. pallies that wear plate has the highest crit constant and they have a talent to get mana back from crits?

from what i can see priest just start off bad. we wear cloth. we have low base crit constant. druids still have the lower base mana which makes their spells cost less mana. what is a priest to do for some loving....