That is a pretty broad question and something you need to approach more by just looking at how you want to start of.
Yes it would be awesome to start off with a high end san, high end network, and a bunch of servers but you could easily spend tens of thousands of dollars.
We have worked with a few smaller fileshare hosts and many of them go with either RAID5 or RAID10 on a webserver. That can get you a few TB of space and provide some room to grow.
Also keep in mind what type of files you want to host, smaller versus larger, as that too can make a change.
Bandwidth is easy, any datacenter can help you out with that -- at a cost.
What you should do is set initial goals, say something like 2-3TB of space and be able to push 500Mbps of bandwidth. When you do that start looking at the BW bill, that something you can stomach until the site makes money?