While on final approach to land, about 150 ft above the ground, the pilot maneuvered and descended the airplane away from a bird. The pilot then realized that he was on a lower approach path to the runway after he observed an airport perimeter fence, but felt that he could still perform a safe landing and increased engine power to continue the approach. The airplane’s left main landing gear then struck a fence post and the pilot initiated a go-around to return to the departure airport. After unsuccessful attempts to verify the left main landing gear was extended and locked, he initiated a landing with full flaps and in a right-wing low attitude. As the airplane touched down, the left main landing gear collapsed, the airplane veered left, exited the runway, and the left wing struck a runway sign. The airplane sustained substantial damage to the left wing. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.