Pond Cost. The cost to build a backyard pond can vary greatly. The size, style, materials and equipment you select will all impact the final price of your pond. You can expect to pay between $5,000 and $20,000 for a custom pond.If you want extra features such as a waterfall or stream, expect to pay an additional amount relevant to the size of the feature. Additionally a bridge or stepping stone pathway that crosses the pond will add to the total cost.he size, style, materials and equipment you select will all impact the final price of your pond. You can expect to pay between $5,000 and $20,000 for a custom pond. If you want extra features such as a waterfall or stream, expect to pay an additional amount relevant to the size of the feature.