How can I start an investment fund like Berkshire Hathaway, and how much money do I need?

You have to be very intelligent, know how to pick stocks wisely, be affiliated with numerous banks, and be worth millions of dollars. Basically all you would need do is create a fund name and pool your own money into the fund and then diversify it. Once you are making money, you have your fund's name registered with the securities and exchange commission. After completion of tons of paperwork and show proof to the exchange commission you know what you are doing, then you can sell stock in your fund. Read the story of Michael Price. He created the the Beacon funds with not much money at all and sold them 10 years later to Franklin Funds. I bought stock in his company 15 years ago and have never lost money.