Since you have that nice sized plasma, I wouldn't want to skimp too much on the sub. An SVS PB10/12-NSD or HSU VTF-2 MK3 should work very well.
Are you using the Bose cubes/bass module system or the larger box type speakers (301, 501, 901)?[/QUOT
I have found a local dealer who will match online prices he does not carry these subwoofers. He does carry B&W do you have a reccomendation for that brand