I did it.  I ordered all the fabric and most of the notional items for my future waterproof parka.  The total, not including $21 in shipping:

Yeah, I could buy a waterproof jacket for that much, right?  Not so fast.  Just to make sure I couldn’t get what I wanted in RTW, I saw that Land’s End had this one:

But it’s not in stock in my size in a color I’d want, and the last few times I’ve tried a Land’s End jacket the sleeves were too small.  The fact that it’s almost sold out tells me that this is an item in demand for plus sizes.  I could not find one like it for the winter months.  Yes, there are raincoats, but nothing “technical”, meaning truly waterproof and breathable.

I’m going to stay pretty close to my last jacket, modifying the hood to cover more of my neck, and maybe adding a drawstring waist.