Everything depends on what type of business you want to start. You could sell items on ebay and have very little start up costs. If you are looking at a brick and mortor location then you will have to take into account: rent, utilities, advertising, salaries, inventory, office supplies, fixtures. I know of individuals who started internet businesses with their own website for around 10k which included website design. Whatever you determine your costs to be add another 30% for unexpected expenses (they always come up). You should also plan to have enough cash for running the business for several months as you will be running in the red initially and many businesses fail because they run out of money before they ever had a chance.