Bull, they make good profits on the big ticket electronics
Then something has changed a lot since I changed careers from being a salesman (not for Circuit City, I sold IT equipment mostly, but the company also sold stuff like big-screen TVs and the margins were not good).
And who sets the margins that low in the first place?
In a very competitive market, someone will be the price leader. Odds are, that someone is bigger than you, sells higher volume, and therefore buys more volume, and therefore buys at a better price. You match their prices (or at least get close) and sell at a low margin, or you sell nothing, especially when the economy is sour like this. You make it up by trying the get the buyer to also buy higher-margin items (accessories, cables, service plans) from you as well, and bring up your overall profit margin for the sale. Resellers will sometimes even have to deal with competing against the direct sales of the very manufacturer whose product they're trying to sell.