There aren't too many reasons to spend the time and money necessary to build your own social network from the ground up. Even big brands with large budgets regularly use existing social networks instead of building from scratch.

Ning.com is the world's largest platform for building a customized social website for your business. You can quickly and affordably set up a social network that integrates with the major sites and has enough customization to meet the needs of most social audiences. And since the Ning platform fee tops out at only $600 per year, you'll have $149,400 to spend on marketing your network in order to build your following.

You could also spend some of that money customizing the look and feel of your Ning network with custom style sheets, splash pages and plugins to the Ning API. Ning also allows you to generate money from your social network in a number of ways, including advertising placements and paid access. This can be helpful if you need to make money to offset some of your development costs.

Another option is to customize a presence on Facebook Pages using Facebook applications and customized programming. You can find the information for customizing a Facebook presence and integrating it into your own website here.

Related: 10 Laws of Social Media Marketing
Related: The Top Five Social Media Mistakes