EXCLUSIVE: Ryan Seacrest may be rapidly becoming one of the richest guys in show business in front of and behind the cameras, but he doesn’t like paying commissions. I learned yesterday that Seacrest, who’d been a longtime client of the William Morris Agency pre-merger, informed WME Entertainment post-merger that he didn’t want to pay the agency’s fee on the differential between his new pact and old pact on American Idol. (Some sources say there was also a dispute over commissions on his radio contract.) I’m told that commissions had been a sore point between Seacrest and the Morris office for years. WME refused to cut him a special deal. “When he pushed back, WME said, ‘We can’t represent you then. Either stay and pay full commission and together we’ll keep growing and expanding and servicing your reality business. Or leave.'” That’s when Seacrest took a meeting at CAA. By the end of day yesterday, Seacrest hadn’t yet made a decision to leave WME. (Some say he was pleased with the reality TV department there, other tell he wasn’t.) Today he left.

What surprised just now is that even rival agencies to WME are describing Seacrest to me as a “grinder” and “scumbag” for trying to negotiate lower commissions. A year ago August, I asked the question whether Seacrest was in play after his longtime William Morris agent Adam Sher left the rep business to run Ryan Seacrest Productions. Though Seacrest still had representation at Morris by John Ferriter, who’d been in 2nd position, I fully expected every major agency to make a run at Ryan and his very hot business. It was assumed that Sher would protect William Morris where he’d been an agent for 15 years. But, after the Morris merger with Endeavor, all bets were off. Now Sher helped guide Seacrest to CAA.

For those who aren’t in the know, Seacrest is much more than just a fey TV personality with no discernible talent. But as famed TV critic Tom Shales wrote in a great piece called “Ryan Seacrest Inc”, Ryan is trying to mimic Rupert Murdoch. (Others think he’s aping Dick Clark or Merv Griffin.) The Viscount of Vapidness is paid an estimated $12.5 million annually for hosting American Idol, not counting all the ancillary gigs he’s lined up. And he’d just signed a rich new contract that will pay him $15 million annually (for a total of $45 million) to keep him on American Idol through 2012 in a deal that also makes Ryan exclusive in primetime to 19 Ent owner CKX. UPDATE: Seacrest’s side maintains the new contract was negotiated by Ryan’s attorney Craig Jacobson, not WME.

The Seacrest empire already includes a multi-year megadeal with Comcast, where he has first-look rights through August 2011. He has a 3-year, $21 million contract with E! Entertainment Network to host its special event programming and Red Carpet coverage as well as an overall production deal there in which he shares the ownership of the shows he creates. He has investments in eight Southern California restaurants, runs a half-dozen media companies and recently launched “The ‘R’ Line” fashion label. And this year he took 3 hours of his daily 5-hour L.A. radio show national, via syndication — and his own advertising company retains 10 minutes of the commercial time to sell on its own, so that the profit goes right back to Seacrest. He does those insipid toothpaste commercials because of a relationship with Procter & Gamble. Seacrest now has lotsa little companies: Ryan Seacrest Productions, “On Air With Ryan Seacrest,” which employs about 20 people; “Top 40” radio has a staff of about 15; Sea Calm, which is the radio division; and Seacrest Sales, which is the sales division. Seacrest told Shales: “The challenge for me is taking all these parts and figuring out how they can come together to make a big media company.” That now becomes CAA’s challenge, too.