How much is a bag of potatoes?

I know how much it is to buy potatoes: 47p

I know how much it is to buy a tin of beans: 23p

I know how much an essentials tube of toothpaste costs: 50p

I know how much it costs to send a rocket to Mars: £4 585 280 400.00 (4 billion, 585 million, 280 thousand, 400 pounds)*

I know what is really essential.

* Mars One estimates the cost of bringing the first four people to Mars at US$ 6 billion. This is the cost of all the hardware combined, plus the operational expenditures, plus margins.