After deciding to separate the back yard to keep the dogs in one part and allow a dog free zone for the children, someone suggested using wood pallets for a money saving way to make a low fence. It turned out great and some was also used on an inside wall to give a rustic decorated look. The cost (apart from purchasing screws) = zero.
Most hardware stores, throw away pallets after use and they can be found littered around the refuse bins. There are many web sites that offer tips on using wood from pallets.