FOUR YEARS ago, seven young unknown actors were given $750 a week and the break of their lives, a chance to perform their irreverent brand of comedy on network TV -- late at night and live from New York.

"When we first began, there was nothing like it on the air, and we had a kind of crusade feeling," said "Live" producer Lorne Michaels, almost wistfully. "It was a feeling of us against them -- against the network, against the conventional wisdom of TV at the time. The intent was more pure. We were incredibly naive."

But now sitting in his newly redecorated office overlooking Studio 8H at NBC headquarters in New York, Michaels is no longer the counterculture creator of an outlaw TV show. At 34, he's the founder of a booming show-business dynasty.

"Live" is regularly seen in prime time now. The players are movie stars and recording artists. They have managers, agents, publicists, personal secretaries and limousines. Several are milionaires; the rest may soon be.

"They're all on their way to becomin g the highest-paid performers in the movie business by next year -- the speed with which their picture prices are going up could set a record," said Sean Daniel, vice president of production at Universal Studios, which is largely responsible for the inflated spiral.

"Animal House" has returned $71 million to Universal, the studio said, and has sparked demand for high-energy satire movies padded with "Live" talent.

"After 'Animal House,' all the great bloodsuckers out here realized, 'Hey this is business,' and it became a rush to 'Saturday Night Live,'" said Bernie Brillstein, manager of John Belushi, Dan Aykroyd, Gilda Radner and producer Michaels (who recently signed with Warner Bros. Studios to write, produce and direct his own movies).

Though Belushi was paid a "nominal" sum for his starring role in "Animal House" (Universal's biggest grosser last year at over $100 million, several sources said that he and Aykroyd since have turned down as much as $1.25 million each to star in a movie. They will soon appear in Universal's World War II farce, "1941."

Bill Murray supposedly joined the millionaire club from his starring role in the summer-camp parody "Meatballs" distributed by Paramount Studios. Though the part was written with him in mind, Murray didn't commit himself to the picture until the second day of filming, according to "Meatballs" producer-director Ivan Reitman. In addition to above-the-title credit, the actor received a "bunch of points" (a percentage of the film's profits), said Reitman, who put the cost of the movie at $1.5 million and the U.S.-Canada box-office gross to date at $39.5 million.

Formerly with the National Lampoon, 32-year-old Reitman also coproduced "Animal House." Both movies currently are on the auction block for sale to TV. "The first bid for 'Meatballs' was $7 million," he said.

Murray recently completed filming on his starring role in Universal's "Where the Buffalo Roam," based on the manic life and times of journalist Hunter Thompson. Currently he's starring with Chevy Chase in Orion Pictures' country-club send-up "Caddyshack" being filmed in Florida. The latter is directed by Harold Ramis, who co-wrote 'Animal House" with Chris Miller and "Caddyshack" producer Doug Kenney (both of whom are National Lampoon alumni). "Caddyshack" was co-written by "Saturday Night Live" writer Brian Doyle Murray, Bill's older brother.

Two other "Live" writers, Rosie Schuster and Alan Zweibel, are working on outside movie projects, according to Brillstein, who also manages them. Gilda Radner turned down the role of Olive Oyl (opposite Robin Williams) in Robert Altman's (and Paramount Pictures') upcoming "Popeye" project because she didn't want to go on location to Malta for four months, Brillstein said. He added that his clients Belushi and Aykroyd have turned down "satire after satire" from the likes of Warner Bros. Studios, Columbia and Paramount Pictures. Of the entire "Live" lot, the manager boasted, "They've become the Beatles of comedy."

Despite reports that "Saturday Night Live" is dying, the season premiere (hosted by Steve Martin) was "our highest-rated ever," said Michaels.

The show debuted in 1975 with a 6.7 rating and 23 share (in ratings, 1 point is approximately 1.5 million viewers) and the numbers have been climbing since. i

Between the '78 and '79 season premieres the numbers jumped from a 12.5 rating and 37 share to a 16 rating and 47 share.

In fact, "Live" is the highest-rated late-night program in TV history, having forged what has been called "the best demographic in TV" -- an audience dominated by 18-to-34-year-olds, the big-spending movie-going and record-buying public. According to an NBC spokesman, the network currently charges sponsors $120,000 per minute of commercial time.

With no production costs to speak of prime-time "Best of Saturday Night Live" is an even bigger financial bonanza: $130,000 to $140,000 per commercial minute, based on the premiere's 31 share of the audience. Since then the numbers have gone down: a 29 share the second week, a 27 share the third.

According to one network source, NBC's decision to put the "Best of . . ." program on the air simultaneously indicates that "there's a feeling that the show won't be around long, so they're trying to make as much [money] out of it as they can while they can." An NBC spokesman confirmed that the network currently is offering the show for syndication but wouldn't comment on the asking price, which is rumored to be high.

Another line of thinking holds that Belushi's and Aykroyd's presence in the reruns will help to lessen the impact of their absence from the new shows. The pair were featured as the Blue Brothers on the prime-time premiere, which aired Oct. 24. They were seen again that week (Oct. 27) when the third late-night show of this season was a repeat from the 1978 season, generally regarded as "Live's" creative high point. Many observers believe that the show has been going downhill since then, succumbing slowly to success and ennui.

Even Michaels doesn't deny that some of the show's former spirit has flown. "Back then, nothing mattered in anyone's life as much as the show," he said. "You could work for 16 or 17 hours, then go back to someone's house and smoke a joint and talk for two or three more hours, and out of that would come another ides for the show.

"The fact that we were an underdog and didn't have much money to do the show only gave it more meaning," he said. "There was no sense of decadence, no lack of purpose. It was never hard to motivate people to work or want to be here."

Things have changed around Studio 8H. During a recent afternoon of rehearsal, security was so tight that a visitor was accompanied everywhere, including to the locked restroom door, by an NBC publicist.

Dan Aykroyd and John Belushi weren't there, of course, having departed the show for good with one year remaining on their five-year contracts. Currently, they're in Chicago filming (on a closed set) their Blues Brothers movie, rumored to be a $20 million-plus production. It's being directed by John Landis, who did "Animal House."

Gilda Radner was seen momentarily in a hallway, but later could not be located. Radner has filmed a version of her recent one-woman Broadway show (the movie is produced by Michaels and directed by Mike Nichols). She has a comedy album about to be released by Warner Bros. Records and has signed to star in her first movie, "First Family," from Warners.

Laraine Newman strode quickly across the set once. "Laraine's been a little uptight lately," a spokesman said. Newman is set to star opposite Dudley Moore in the movie "Wholly Moses," produced by David Begelman (his first independent production for Columbia pictures since he stepped down as head of the studio last year in a cloud of scandal). Since the film production will run concurrent with "Saturday Night Live," she'll be commuting from set to set.

Bill Murray was glimpsed through a partially closed door, watching an episode of "Buck Rogers in the 25th Century" on the TV. He will be commuting, too, from the set of "Caddyshack," his fourth movie in rapid succession.

Garrett Morris was not on the premises. He's appearing in an off-Broadway play and recording a music-comedy album for MCA Records. He didn't perform on the show that week.

Jane Curtin was on her way to the studio from Eugene, Ore., where she was filming "How to Beat the High Cost of Living," her first starring role --flying in on a Thursday and leaving again Sunday morning. In a recent (and rare) interview to promote her movie, Curtin told the Los Angeles Times that she would not be interested in working with the "Live troupe after the show runs its course."

Part of the unavailability on the set that day stemmed from a recent unflattering article in TV Guide, said associate producer Jean Doumanian. Titled "Saturday Night Moribund," the article rapped the players for being aloof and uncooperative with the press and criticized the show for being less funny than it once was. "It was an out-and-out attack," Doumanian said. though she admitted she hadn't read the article. "So everyone's a little gunshy."

With all contracts up at the end of this season, it seems likely that "Live" won't be alive next year. Michaels didn't deny that possibility, but he asserted, "My job is to uphold the quality of the show for as long as possible, and that's what I intend to do.

"I haven't found a job as good as this one. It has everything I ever wanted. It's not as completely satisfying for an actor because you never get to do it again and make it better. But I love the raggedness and the raw feeling and the fact that you can't possibly make 90 minutes great. The effort has a kind of Sisyphus quality to it -- because you know it's going to fall down in the end. It somehow doesn't matter, you just try harder."

Why would he stay when all his proteges have gone on to bigger things? "Because I need the aggravation," he said. "With 25 million people watching you there's nothing in any way comparable to public humiliation on this scale." y