These days there are many free tools that you could use for your business. In my opinion most of these free tools are better than some of the paid ones.
For example, if you have something to sell, you may want to look into Oscommerce which offers an open-source online shop platform.
You can drive traffic to your store through free shopping comparison sites such as Google Shopping, TheFind, Shopwiki, Bing Shopping and many others.
Then of course there are CMS open-source programs that can work for any business. Wordpress and Joomla are definitely amongst my favorite ones to use.
Let's not forget social media -- Facebook, Google+, Twitter and many others.