Your bread and butter..

This job is my "bread and butter", so

A ballpark figure / a ballpark estimate

She gave us a ballpark figure for the cost because she

Cook the books / cook the accounts

He cooked the books of his business, and now he

Deep pockets

Harold has very deep pockets, and

Dirt cheap

If you buy something that's dirt cheap, the quality will probably.... 

Easy come, easy go

Pete lost a hundred dollars on a bet and then said "Oh, well. Easy come, easy go". He wanted us to think that

Easy money

Larry was always trying to think of ways to make easy money because he

Your bread and butter.. This job is my "bread and butter", so