Eventually I am going to update to the magento enterprise addition that will cover all the functionality that I will need. But for now I just need to use magento and customize to be a basic private sale site that is very similar to lot18 (check the site lot18).
So I will need to
1. install magento
2. update the skin to my design and put up the main signup-request invite page
3. customize the code for private sales (there are some magento extensions that cover a lot of the functionality as well
the main private sales features are relegated to only members are allowed to see pricing. users can send invites to friends for them to get into the system and people can arrive in the main page and request invites (like on lot18) and you can track Friend Referal, tracking, rewards (credits)