Why do you think a motor has to be new? Many of my home built machines have used motors. You don't say where your from in your Profile, but I'm willing to bet there is an industrial surplus place close to you, and motors there are way, way cheaper than say Graingers or someplace like that. Or did I mention Craigslist? Believe me I'm about the most frugal person you'll ever meet, and it can be done cheaply. They just won't deliver it to your door.
And as far as having stuff fabricated, unless you have some one that can do it for free, buying it new will be way cheaper. And even a 1/64 inch off will make your life miserable. I know because I'm a retired machinist. When it comes to lining up stuff like a pump and motor, even the thickness of a sheet of paper is a problem. That is why they came up with C face motors, adapters and pumps, takes all the hard work out of the equation. But even then they use a flex coupling like a Lovejoy.
And as far as having stuff fabricated, unless you have some one that can do it for free, buying it new will be way cheaper. And even a 1/64 inch off will make your life miserable. I know because I'm a retired machinist. When it comes to lining up stuff like a pump and motor, even the thickness of a sheet of paper is a problem. That is why they came up with C face motors, adapters and pumps, takes all the hard work out of the equation. But even then they use a flex coupling like a Lovejoy.