According to the pilot, while taxiing for departure to runway 3, the airplane encountered a wind gust from the left. The wind gust lifted the left wing, the airplane turned 180 degrees, and traveled down a 20 to 40 foot embankment. The airplane came to rest inverted and sustained substantial damage. Examination of the airplane showed damage to the left wing, vertical stabilizer, and empennage. The pilot estimated the wind speed at 45 knots.