where do i go to get my fishing level above 150..?

I'm pretty sure that it is a book from Booty Bay. I could be wrong, and don't quote me, but I'm thinking its the book.

expert fishing - the bass and you

obtainable in booty bay from old man heming on the eastern (inn and bank) side of the city.
http://thottbot.com/c2626
from my experience, this is a much cheaper solution than the auction house.