Hi, I just bought a Markbass CMD JB PLayers School combo. It was a Markbass I could afford and I like it a lot. I just sold my Hartke rig and am interested in adding an extension cab only all the Markbass cabs I've seen have been more expensive than the amp I bought. Apparently they do not make an extension cab with owners of this amp in mind. What do you think would be a good, yet not insanely expensive, extension speaker cab for this amp? I could spend as much as $500 although I would prefer not to spend that much. Thanks for the help.