If you want to carry your kids in parades, then a cart with a seat is probably a better starting point. Most people seem to end up with a few different vehicles to hook their dogs to, since each vehicle has a purpose. The Books page lists some books that deal with carting and drafting. If you run across any more, please let me know . See the Clubs page for more information and contacts.
Prices are very reasonable.
Some of the vendors on the Equipment Vendors page also have plans available. Carting equipment is sometime difficult to find. The Equipment Vendors page lists any known suppliers, and the page is updated rather frequently as new vendors are found, or current vendors add more products. Some of the vendors run their own web sites that showcase their products, and these are really interesting to view. Note that shipping some of the larger items becomes a bit of an expense itself.