Too many cooks spoil the broth

All that glitters is not gold

B ead and butter – This is your livelihood or the source of your income.
A ballpark figure - a rough estimate - American English
If you give a ballpark figure or a ballpark estimate, you give a number which you think is fairly close to the actual one.

A nest egg
If you have a nest egg, you have money put away for the future.

A vested interest
If you have a vested interest in something, you have a strong personal interest in it because you stand to gain from it.

Cook the books | cook the accounts
If someone cooks the books, or cooks the accounts, they keep inaccurate accounts for a business, usually in order to pay less tax.

Cost the earth | charge the earth
If something costs the earth, or they charge the earth for it, it's very expensive.

Deep pockets
You can say a person or an organisation has deep pockets if they have lots of money.

Deep pockets and short arms - a person is mean with their money

Money can buy you friends but it can't buy you love

Dirt cheap
You can say something is dirt cheap if it costs very little money.

Easy come, easy go
You can say " easy come, easy go" to express the idea that if something comes to someone easily, such as money they get without working hard for it, they can lose it just as easily and it won't matter to them much.

Easy money
You can say " easy money" to describe money that someone gets without having to make much effort.

Feather your own nest
If you feather your own nest, you use your position or your job illegally for personal gain.

Feel the pinch
If you are feeling the pinch, you're finding it harder to survive on your income.
For my money
You can say " for my money" to mean the same as " in my opinion".

Go out of business
If a company goes out of business, it stops trading and closes down.

Grease someone's palm
If you grease someone's palm, you pay them a bribe.

In the black
If a person or a company is in the black, their assets are greater than their debts.

In the red
If a person or a company is in the red, their debts are greater than their assets.

Kill the goose that lays the golden egg
If you kill the goose that lays the golden egg, you destroy something that has made you a lot of money.

Made of money
If you are made of money, you have lots of money.

Make a killing
If you make a killing, you make a lot of money from a sale or a deal of some sort.

Make ends meet
If you make ends meet, you earn just enough to pay for a place to live and your daily expenses.

Pay the price
You pay the price for doing something when you experience the unpleasant results of doing it.

Pay through the nose
If you pay through the nose for something, you pay more than the usual price for it.