Where could I find a cheaper dog driving cart?

Dog carting is amazing. A fabulous workout for your dog and fun for you as well. You can't force a dog to "pull" so it only works in a totally positive environment...no wonder those dogs look like they're having so much fun carting. They are! I did locate several different vendors for you as well as a do it yourself option : This cargo  cart is great for a medium to large dog. Weighs 70lbs. Has a  third wheel so there is no weight pushing down on the animal. Springs under the seat make a comfortable ride. Our carts are now equipped with disc brakes for you and your animals safety. Some assembly tools are included. The basic competition cart from Wilczek Woodworks, is hand built to order, and carefully crafted. Multi-position shafts and axles make them adaptable for most any dog. A weight insert turns any cart into a competition vehicle.We never scrimp on looks! Our dog carts are beautifully finished -- and touches like removable side slats make our carts picture perfect.... The Mini Chariot, for our smaller four legged friends. The Chariot is 11” long, 15” high with an overall length of only 3’. It weighs less than 5 pounds constructed with a maple hard wood. The shafts can be adjusted in height in ½” increments from 10” to 14” The inside spacing between the shafts is 9.5”. If you would like to build your own (not competition specs) I found this site for you. If you do choose to build, SAFETY should be the number one priority. A cart that falls apart, is unbalanced or has sharp edges is dangerous.