Kimora Lee Simmons just joined a star-studded cast of homeowners ... but it cost her a pretty penny. Russell Simmons' ex-wife plunked down a king's ransom for the 7 bedroom, 11 bath home in Beverly Park, a wealthy gated community where tons of celebs live ... including Denzel Washington, Mark Wahlberg, Eddie Murphy and Sylvester Stallone. The swanky pad has a gourmet kitchen, conservatory, wine cellar and a home theater. The outdoor pool's not too shabby either. Kimora and her hubby -- ex Goldman Sachs banker Tim Leissner -- dropped $27.5 mil on the Mediterranean villa. Hey, famous neighbors don't come cheap.