Almost every Microsoft product key can be obtained from this Invite.
By using admin account you can sell invite codes and distribute them.
Your subscription will be valid for 3 Year and keys will be valid for Lifetime

Selling MSDN Invites for 40$ and the admin account for 150$.With the admin account you get 4 invites in total so you can sell them further.Additionally,you get 150$ of windows azure credit each month for 1 year.