Creating a blog portal with unlimited blogs

Hi,

I am a web designer with 7 years web experience with no experience of creating blogs at all. My company is putting together a pitch for a major sportswear company and part of the pitch is a website that has normal marketing/product information but also an area where users can create their own online training blogs.

The site needs to be branded and designed by us and on the homepage have links to different categories like – most recent blog posts, most popular blogs, different categories of blogs etc. Users need to be able to sign up and create their blogs automatically and users need to also be able to sign up automatically to post comments on other users sites. We need all the usual administrative options to be able to ban users etc and spam protection etc.

There would be a budget for this to the tune of one to two thousand pounds but obviously cheaper is better.

From what i can see wordpress is a package ideally suited to the single standalone blogger but what we are looking for really is a blog “portal” package – where essentially we can have unlimited users creating an unlimited amount of blogs all with the same branded template.

My question for you guys is does anything like this exist at all? Can you buy off the shelf packages that allow you to set this kind of thing up? I have had a look over the web and havent really found anything yet but I thought that someone here might be able to recommend something.

Thanks in advance for any advice/recommendations.

Cheers