GREENHOUSE on Varick Street is taking competition to the next level. The club’s owners bought the Internet domain name Provocateurnyc.com after “buzz started around the Provocateur nightclub,” which opens next month in the Hotel Gansevoort, a source said. The Web site directs visitors back to Greenhouse’s site. A Provocateur rep told Page Six, “This is like Payless stealing the Christian Louboutin domain name.” A rep for Greenhouse didn’t return calls.