While I would never spend the kind of money Yakima wants, I have to ask why would you want something heavier duty than a trailer that is designed specifically for what you want it to do? Buying or building a 2000 lb gvw trailer to haul less than 500 lbs of gear will ride too stiff and be harder on your gear than the one designed for the weight you want to haul. The harbor freight trailer will do what you want but it's probably not any heavier duty than the Yakima trailer.
Phil