First of all, you should buy speakers that fit you best and sound the best to you. That's the 1st step before arguing about which is more cost effective. That 1st step should weed out most speakers.
Then the 2nd step is finding out which one you can get for the best price, assuming you have more than one speaker that fit you best. If the ID brand is cheaper, you buy that. If you can get a better price on the B&M brand, then buy B&M.
You can argue all day long about which is more "cost effective" and "the middle man" and economy of scale, etc.. It doesn't get anywhere.
You buy the speakers that sound the best to you at the best price you can get. Period.