I'm looking for a basic web-based file management application. It must have an affordable price, and fairly easy installation would be a plus. ASP.Net / IIS based would be easiest for me to work with. Basically, I'd like it to create a secure web site where myself and a few people can exchange various types of files, etc. I'm looking for a package I can install on my own server rather than a web-based service, as I think I can get more space at a good price point this way.

I could go custom coding, but I figure this is such a generic need, there must be something already mature out there at a decent price. What has worked best for you?