All discussion about machines aside, learning to sew marine projects certainly adds a whole new realm to your ability to enhance your sailing enjoyment. Soon you'll be creating all sorts of convenient projects for storage and comfort such as pockets, ditty bags, curtains, hatch covers, etc. in addition to big projects like biminis and cushions. It does take a lot of time though. Whatever machine you use, the Sail-Rite videos are great learning tools. Canvas and upholstery are different than clothing skills, my wife was a professional seamstress for clothing and poo-poo'd such things as pre-creasing seams or basting tape which is the cats meow for canvas. The Sail-Rite kits are great for getting started and learning the skills, techniques, and common materials, but I find the designs somewhat spartan and as you said, expensive. If you want a more elegant look, you'll have to do more design work, noticing what other people have, and decide what features you want.
A Bimini kit might be a great first project with the understanding it is a learning kit and you'll probably want to redo it better. For example, do you want extension panel between the Bimini and dodger? side curtains? full enclosure? Sail windows?