Server / Access resources needed for major site?

What type of resources / programming would it take to develop and maintain a site like this:

1.) Huge amount of new records added daily (150,000 -250,000 per day)
ramped up to this amount over time.

2.) Data active for 6 months and then stored for 3 years.

3.) Approximately 200,000-250,000 people accessing the site simultaniously at any given time doing complex searches via web. Free and paid access.