SereneLife 50′ Ninja Slackline Obstacle Course For $59.99 Shipped From Amazon This was selling for $120.55 yesterday and is now the lowest price ever from Amazon. ULTIMATE NINJA OBSTACLE COURSE: Our 50ft Ninja Slackline includes 8 thrilling obstacles designed to challenge and entertain. Enjoy slackline, ninja wheel, gym rings, climbing rope, monkey bars, 5-step ladder, […]