Why is it that VPS and dedicated servers offer so little space and bandwidth compared to shared hosting? Most of the shared hosts I see now offer unlimited space and bandwidth. I would think that shard hosting would offer less space due to more accounts on the same box.

The site that I am working on is fine here now, but if it starts getting a lot of users, it might be an issue. Since people can upload their own media files (without violating the ToS), on a VPS or dedicated server with about 100GB of space I would run out of space after 200 or so users.

Also, are there any good VPS people can recommend? The review sites that I've read all have different ones at the top.