With internet direct you have to factor in the costs of shipping a subwoofer. My subwoofer cost me $100. You also may need to coordinate someone at home when the shipment arrives.
With B&M you have to add in local sales tax to the cost and possibly local delivery ($50 est.)
For $150 difference I would go with the convenience of a local B&M because you can always go pick it up and save local delivery. You can have it now. You took up a lot of the salesmen’s time and you kind of owe them your business, especially if you plan on going back to the store for other purchases or listen to other things. Finally you have real people you can talk to for help, advice and to resolve any problems without a big bureaucratic mess over the telephone and E-mails. (Read the thread about the guy with the Onkyo receiver debacle if you want to know worse case) If you just go into a big box store, then I feel you owe them nothing and are free to go internet direct if it is enough savings.