Imagine that you want a boat. You tell someone to build or buy you a boat, and tell them to send you a bill. What would you get? A kayak? A windsurfer? A boat for waterskiing? A sailboat. A party boat? A cruise ship? A submarine? A battleship or destroyer? You probably would not get what you want. Very likely you would end up with something expensive - that you cannot use.
Before you build or buy a boat, you need a defined goal and a process: