TRY telling billionaires the US housing market is in the dumps. Many of the worlds richest have eagerly been snapping up lavish properties from coast to coast this year. Venture capitalist Yuri Milner broke price records with his $100 million Silicon Valley home purchase, Formula One heiress Petra Ecclestone shelled out $85 million on Los Angeles Spelling Manor, and industrialist scion Alexander Rovt rescued Manhattans Henry T. Sloane Mansion out of foreclosure for $33 million, to name but a few. Even Mark Zuckerberg became a homeowner. But while many billionaires have been busily buying up real estate, one is actually selling. Paul Allen, the Microsoft co-founder that ranks 57th on the Forbes Worlds Billionaires list with $13 billion, is offloading his private island. Allan Island, situated near Anacortes, Wash., is back on the market and at a reduced price, reports the Seattle Post-Intelligencer and Allan Island has bounced on and off the sale block since 2005, when its initial price tag was $25 million. It took a $5.5 million price chop in 2006 before re-emerging with the current $13.5 million asking price. Windmere Real Estate has the listing. Allen bought the island in 1992, reportedly to build a vacation home, before snatching up the Sperry Peninsula site on nearby Lopez Island in 1996 and abandoning his original plans. Forbes