Mugnaini manufacturers a popular wood fired pizza oven that can be used for a variety of open hearth cooking techniques. According to the manufacturer, these ovens are listed with UL and NSF.
With models ranging in size from 9 sq. ft. to 28 sq. ft. (big enough for fourteen 12" pizzas), there is an oven that's just right for your back yard, kitchen, or restaurant.
Based on my online research, you can purchase a very nice oven for the back yard that costs in the range of $3,000 plus installation costs.