Warrior - Tonne is money, friend!
Hunter - Tame is money, friend!
Mage - Tome is money, friend!
Rogue - Crime is money, friend!
Priest - Tithe is money, friend!
Warlock - Time is money, fiend!
Death Knight - Tomb is money, friend!
(I couldn’t think of anything for Monk and Shaman. Please help me out! 
)
Considering mage is the time class in wow and warlocks also deal in grimoires, I’d swap mage and warlock around.
As for shaman, totems are money friend. Monk, Chi is money friend.
No no no, you didn’t get the warlock one right.
The original saying is “Time is money, friend!”. I changed the warlock one to “Time is money, fiend!”
Fiend as in demon 
Monk,
Tea is money, friend
Oh my bad. I’d still have the mage one say time though.
I thought of “Time is mana, friend”, but that would remove the money, and I’m not sure about that…
I like that one even better. Do that.
“Tide is money, friend.” Because, you know. Tides, Mana Tide. Shamans. Etc.
That’s genius! 
“Time isn’t money, friend” for monks, because they’re zen enough to have de-goblined themselves.