As everyone else has said, the Yoshimura pieces are fairly substantial, well worth the price.
If you were going to make it yourself you would need a good welder (wire welder would be fine, Tig would be better), about one square foot of 1/4" to 3/8" steel plate, a plate breaker (puts a fold in metal plate- don't know the technical name for it), a drill press, a metal lathe (or at the very least the pre-turned stalks to drill out the center section in. True, in bulk metal costs, you would only be looking at $20-30, but throw in how much time is worth (substantial value if you have the skills to do it properly), plus having the tools (none of which costs less than a few hundred dollars, with some going upwards of a few thousand). You will quickly find that to make them yourself, if you don't have a full service machine shop at your disposal, you would be much better off to order the ones from Yoshimura, install them in your garage/driveway, and get on with riding your bike. Even if you have the full service shop you would still be better off leaving the production to a mass production company, than you would wasting your time.
If however you are wanting to do it simply for the joy of building something with your hands, go for it. More power to you, and the world needs more skilled do-it-yourself-ers.
