“Champagne King” Don Johnson is fast becoming the most popular and prolific big spender on the New York nightlife scene. The mogul, who bought a 15-liter bottle of champagne for the Women’s US soccer team at Avenue on Monday, threw a bikini-contest party at SL the next night. The Meatpacking club bounced with 150 inflatable beach balls, and SL staffers wore T-shirts that read, “I Love Don.” Johnson, who sources say dropped a cool $50,000 on bubbly, got on the mike and announced the contest. The winner got a trip to Ibiza to party with him and friends in August. Johnson is CEO of Wyoming-based Heritage Development LLC, which uses computer-assisted wagering programs for horse racing. He gained notoriety after winning $15 million at blackjack in Atlantic City, and was dubbed the “Champagne King” after spending $270,000 for a 30-liter bottle of Armand de Brignac Midas, the most expensive bottle of Champagne ever sold, in London last month.