Wayfair offers 700Lb Giant 60" Platform Tree Swing For Kids And Adults Waterproof With Durable Steel Frame for $82.99 (orig. $159.99) with free shipping.

Product Description:
Large 60" Platform Swing, Weight rated to 700 pounds, spacious and strong enough for 3 kids or two adults to swing for a long time. You can install our swing almost anywhere indoors, outdoors, or in a playground that has a horizontal branch or pole. With our hanging kit, you can install this in minutes on a swing set, tree, pergola, and more. Take it with you camping or to your friend's backyard to share the fun.