BOCA RATON, FL.- Say goodbye to the twirling carousel, the rows of perfectly shined classic cars, the player pianos and jukeboxes. They’re selling all the neon signs, the slot machines, the antique guns, the Tiffany lamps, the hulking chandeliers. There will be no more rare organs or vintage gas pumps or the Army airplane gliding overhead, none of this out-of-this-world collection that took a lifetime to amass. It will all be gone soon, before most people ever knew it existed. Two brothers, Bob and Paul Milhous, are liquidating their one-of-a-kind private museum after spending decades scouring the world to find its gems. The Milhous Collection, as the items in their 39,000-square-foot building have become known, head to the auction block next month, estimated to fetch around $40 million. “Our time’s kind of up with them,” said Bob Milhous, who at 75, is the elder brother. “It’s time to move on.” The men first started picking up