I built this cart to get my kayak with trolling motor from the truck, campsite to the water and launch.
The cost was 2 wheels and stainless steel bolts, nuts and washers.
Amazon.com: Rambo Bikes Canoe and Kayak Trailer Cart - Heavy-Duty Kayak Cart with 300lbs Maximum Capacity - Extendable Bike Trailer - Adjustable Steel Frame, Padded Contact Points, 16"x3" Wheels for Any Terrain : Sports & Outdoors
Photos to follow when I get help downloading them.