Recording artists who endorse products or license music to advertisers used to be labeled sellouts; now they are entrepreneurs. The year 2004 will be the first in four that the music business has managed to increase American album sales. But sales are up about 2 percent, a meager showing over last year’s weak figures. That places high pressure on artists to ferret out other sources of income. The stars-turned-marketers range from Britney Spears (television movie, fragrance) to Lil Jon (energy drink, adult film and soon an authorized Halloween costume). But few have out-hustled 50 Cent, the Queens-bred rap star who has been striking deals with the urgency recommended so starkly in the title of his debut CD, “Get Rich or Die Tryin’.” Sources close to the artist say 50 Cent’s forays into fashion, entertainment and even beverages in the last 12 months or so generated income in the $50 million range. Here’s a rundown of his ventures.