Is it possible to give a website the following features without spending huge amounts of money?

1) Internal messaging between users
2) Automatic posting of content users submit
3) Logging in
4) Automated screening of submissions for illegal characters
5) Automated screening of submissions for whether things like passwords match those on record or are incorrect

I consider huge amounts of money to mean at least one thousand dollars. Even as much as one hundred is a lot, too, though.