When looking for parts for my vintage bike, Amazon is not the first place that comes to mind. But if you're okay with inexpensive mass-produced parts (as opposed to expensive custom parts) then they have you covered. For example, this combo of black Clubman handle bars, bar end mirrors and grips is a good value at $56.50 plus shipping. I bought similar bars, the same bar end mirrors and similar grips separately for about $10 more than that price and my grips were not open-ended - I had to cut them myself.
Of course, despite what you may see on ebay, a set of clubmans and bar end mirrors does not a cafe racer make. And adding these parts will not automatically make your bike worthy of the front page of Bike Exif or Pipeburn. But if you want an inexpensive way to change up the look of your vintage bike then this is an good option at a good price.