The $399.99 on lifetime is the best you can get. This is the MSD price because its a secondary service box on your account. Should the first box fail, or not even connect to Tivo regularly, the next Tivo you add will be $499.99 on lifetime.
Series 2 (Retired, sold)
TiVo HD 1TB (157 HD Hrs, PLS, "S3HD")
Roamio, Oh Roamio!
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!