The pilot reported that while practicing landings in a tailwheel-equipped airplane, during landing roll in gusting wind conditions, the airplane started to veer to the left. Despite the pilot's control inputs, he was unable to maintain directional control. Subsequently, the airplane began to bounce several times and the main gear collapsed. As the airplane skidded to a stop, the right wing struck a sign which resulted in substantial damage to the airplane. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.