Oh im sorry, I didnt see you only need 20GB bandwith. My site only goes down to 300 so, I can provide you the following. (The exact package you requested.)

20GB Diskspace.
20GB Bandwith
Unlimited All
98% Uptime
Cpanel & fantastico
Support
$9.99/Monthly *Paypal*

Contact Us.
http://www.jexhost.com/contact.php