What is the cost of building a small ship?

This ultimately depends on your purpose for the ship. If it is to ride around a small lake look in to the low 1 to 2000 dollar range. But if it is to sail in ocean like waters double or even triple the price. A lot of the price of the boat stem from tools, parts, and extras so by narrowing down what performance your looking to grasp from your boat you will come up with a basic price.