Buy the speakers and if you later feel you need to get a self-powered subwoofer--then get one. No reason to get one before YOU listen to your set-up at home. If you feel you need one after listening to some DVD video's that have deep sub parts, such as Top Gun and other such movies--or some music that has deep passages, you can always get a Paradigm 2200 or HSU-VTF-2 is on sale now with free shipping for $449.And Outlaw Audio (in engineering conjunction with Dr. HSU) is releasing the new LFM-1 at $579.
"Resist the Rep"--sounds like a good slogan! Unless he gives you a big discount now for the Paradigm 2200--like at $500. I am sure he isn't going to like you going elsewhere to get the subwoofer if you ever decide to get one. And as subwoofers have no sound quality (unless they are made poorly) any good subwoofer works well with almost any system.