A 4th option would be moving to Arizona cause it hasn’t rained here for near a year it seems. grin They say maybe next week but they say that a lot. I just carry a pullover Patagonia Houdini that turns back the rain well. Mostly it’s used as a windbreaker.
But if you really want to make your own then why not just do it. That might be a satisfying challenge. Less than $20 for a light Frog Togg suit does sound okay to me too. I guess you just have to choose for yourself.