PILOT RECEIVED RUNWAY INFORMATION FROM UNICOM BUT DID NOT RECEIVE WIND INFORMATION. HE NOTICED ON APPROACH THAT THE WIND SOCK WAS POINTING PERPENDICULAR TO THE RUNWAY BUT NOT FULLY EXTENDED. ON LANDING THE AIRPLANE ENCOUNTER A WIND GUST FROM THE RIGHT WHICH EXCEEDED THE CROSSWIND CAPABILITIES OF THE AIRPLANE. DIRECTIONAL CONTROL WAS LOST AND THE AIRPLANE DEPARTED THE RUNWAY. ALL THREE LANDING GEAR COLLAPSED WHEN SAND WAS ENCOUNTERED NEXT TO THE RUNWAY.