What is the minimum amount of funding with which it is possible to start a business? Could a business be started with zero funds?

What sort of business could each member of the group start, with little or no funding? Prepare a (very brief) business plan. Would it be necessary to raise substantial funding to develop the business so that it becomes large scale? How would you define ‘large scale’ (big enough to provide you with a suitable lifestyle; big enough for a stock market listing)?