craiglist clone with some extra features

I need a craiglist clone but with the following features. 1)Users must join the list by providing email address and password. 2)Email address must be verified thru an email sent to the the user. 3) Person replying to any advertisement must be logged in first. So if the person is not logged in, it should take the user to Login page or register page. (could be the same page) 3) All postings should be saved in the DB. 4)Provision to change the password once the person is logged in. All other features of craiglist must be maintained. If you have a done a script like this before then I want to see a demo. Thanks