you are probably just a bit too far for most of the other companies.
don't ferris still do a coach from portsmouth?
other companies are obviously siesta, and another you could look at is inland travel who go from flimwell in east sussex, and have very cheap car parking on site.

thank you jimd-f i have not heard of inland travel will give tham a look, i think Ferris only pick up at Portsmouth if you coach and cruise but will double check, thank you