Since announcing on October 6, 2004, that it had signed Howard Stern to a five-year deal, Sirius Satellite Radio has added approximately 2.7 million subscribers and become a household name in the satellite radio world. The tab: Close to 0 million. Is Stern worth it? The answer depends on whom you ask. Sirius CEO Mel Karmazin, who joined the company in November 2004 and had been Stern’s boss at Infinity Broadcasting and then Viacom before departing in June 2004, says the radio “shock jock” is a good investment. “ There is no question that Howard is worth the money that he is getting paid,” said Karmazin on CNBC’s “Mad Money” show last fall. “As a matter of fact, if he was going to renegotiate today, he would have to get more money because [sales are] really doing well.” Others aren’t so sure. Wharton marketing professor Peter Fader says Sirius would have reached its current 3.3 million subscriber total without Stern.…