The one picture posted above from "TV" is a simple shade system used on one of the boats in the show "Swamp People." Four pipes as uprights with a tarp stretched between. Simple, inexpensive and effective.
This may sound overly simplistic, but it works. When I was younger and poorer, I made a home-made bimini top from some conduit, 1/4" bolts and a silver tarp... Total cost was about $20.
Go to Home Depot or Lowes and buy a few pieces of 1/2" galvanized conduit and one piece of the next size up, which I think may be 5/8", to use for sleeves. It's really cheap, like $2.50 each. Bend two pieces to form the main arch, and then a secondary, smaller arch to fit just inside or outside the main arch, and even a third arch, if desired. Use tap-screws and maybe 6" of sleeve to connect them together.
The reason you make it so the arches "nest" inside each other, is that, instead of buying hardware, you now drill through both frames, and put 1/4" bolts through them, forming the hinges. Now your "bimini" frame is built. Get the smallest sized arch you can find, and figure out how big it must be. Then, if you have a sewing machine, fold the front and back over to make the tunnels that the tubing goes through.
OR if you are poor, like I was, use an office stapler and just staple it many times. It works.
I mounted two blocks of wood and used a single screw through the base of the main arches to secure to the side of the boat. Then I used some nylon strap to make it tight, and away I went!
Believe it or not, this only took me about an hour, and it worked great for a couple of years, until the staples started rusting out. You had to pull it tight, or it crackled when you were running.
Several of my neighbors saw mine, and asked me if I could make them one, and I sold a number of them for the AMAZING price of $60! WO-HOO!!! I was rich!
That being said, nowadays, I would just buy a jon boat bimini. Still, making your own has a certain level of satisfaction. I wish I had some pictures from back then, but I don't. Sorry!
-TH