What is the cost of running a social networking website?

I am working on a project to build a social networking web site from scratch using oracle database and an application server like Tomcat. Can any one with prior experience let me know what is the total cost I can expect to incur in execution of this project? Assumption is that this website will be able to support several million users.What is the cost of running a social networking website?
I have a few experience in social network developments.

Before all, be aware that very few are successful: 99.9% of attempts go down the drain within a year.

Why? Because they are not ADVERTISED by any other means than the web. In other words, if they are not advertised using other medias (tV, radio, papers etc), they do not survive.

So, what is the cost?

A relatively complex social network will cost a few grands to set-up (expect 3-6k minimum for a "decent" site).

To the cost of development, of course, you have to add the domain and the server(s). At start, this is nearly "free": for $100, you have all you need.

Once set-up and fully tested, it needs to be promoted.

Here come the costs. It depends of the type of network you do. A SN for dentists, for example, will need to be advertised in all the specialised magazines for dentists, and that is not cheap.

You want a Facebook? You need a MASSIVE start-up for a few months, on TV and many other medias.

Fail that, and it simply "won't start".

But...

It HAS started, and you get a few thousands members...

The cost of your server will increase dramatically: you need dedicated server at start, and, once you reach the millions, a server FARM (more than one server).

It becomes worldwide? You need servers in different countries... and in different languages!

That means a TEAM of coders, available 24/7, to respond to the demand.

That, also, means powerful BANDWIDTH, a very expensive requirement. A SN like second-life pays several $1000's PER DAY for their bandwidth... But with 35,000 concurrent visitors a day, each one paying a few $... They are covered!



SN like Y!A are successful, because supported by big, large, powerful multinational companies.



In the end, a successful SN can only survice if it becomes a heavy business, with staff, infrastructure, admin and legal department.



That is a totally different ball game as making your own, little "Y!A" on your local server.



Successful websites (SN or not), are supported by serious money and professional staff.

Or they are not successful and go to oblivion a few months after birth.



Several million users? Between 2 and 5 million $ of investment. And 25% of turnover a year profit.