You CAN get by with the basics if you aren't doing volume. A sheet metal brake (not an aluminum siding brake please), hand notcher, sign plotter, hand held jigsaw and some skill is all you need to get started. It's not easy BTW to make them from scratch the old fashioned way. We used to make channel letters wholesale, back when we rode dinosaurs to the shop and it did take time I do know people that still do it that way, but what everyone above said is needed to do it in a modern way. BTW, you don't need an electrical license to MAKE channel letters. It's when you get to installing them and applying for permits where licensing is needed. You can just cut a check to UL or met labs or... and get your certification (yes I'm oversimplifying the process) in a fairly short time period. That alone is ~$5K.
However, unless you are selling a lot of them, it's so much easier to buy them wholesale. Yes you CAN make them cheaper, but why? You can also make bricks cheaper than you can buy them but do you want to? I have a full sheet metal shop (10' shear and brake and box/pan and much more) but when I need letters I usually buy them. Design the job, sell it, hire someone with the licenses to do the installation and collect the check and move on to the next paying job.
Oh, just saw that you are in Canada. IDK what the process is for getting CSA approval.