Many e-businesses can be started with less than $1000. In fact, some can even be started for less than $100. From there is really depends on what you want to do and what business model you want to have (where will your revenue come from)? Will you make money from selling goods and/or services via the Internet or will you draw people to your website with good content and then make money from advertising revenue?
Either way, while an e-business may be easy (or cheap) to start, it may not produce any kind of stable income for a while. Many e-businesses operate purely on start-up capital for a long time and can take years to be profitable and successful. However, if you work hard and have creative ideas, you can make a lot of money starting your own e-business. Just keep in mind that an e-business is not a get rich quick scheme.