The cost of constructing a Zen rock garden, also known as a 'kare-sansui' or 'dry landscape garden', can vary widely depending on factors such as the size of the garden, the quality of the materials used, and the complexity of the design. On average, the cost can range from a few thousand to tens of thousands of dollars. It typically involves purchasing and placing the stones, as well as the installation of other elements like pebbles or sand to represent water. Labor costs, including design and construction, are also significant.