First, I used to break a lot of Carlisle blades, like one or two a year, then I bit the bullet and bought dynalites, which are 8 years old and going strong. So the simplest solution may be dropping cash on high end blades. With that said my least favorite response on the buzz is "go out and buy XYZ"
So as it turns out I'm a DIY addict and have thought about building blades but have not tackled it yet. I see some fairly significant hurdles but if you look at sawyers fancier blades it's got to be totally doable. The hard part as I see it will be attaching the blade portion to the shaft (of the blade) and fitting the male portion of the blade inside the oar. On their dynalites Sawyer uses an aluminum shaft filled with some sort of light epoxy or dense foam, but the AL always looks machined so I'm guessing size wise there is no readily available aluminum stock that fits snugly inside the oar shaft. I also think that AL shaft tapers towards the tip of the blade, then is welded to an AL flat strap that the blade material is then built around. Fabricating all this stuff without AL welding abilities or metal milling is where I see the main issue. That may be clear as mud and if so I'm sorry but it makes sense inside my feeble brain.
Building something like sawyers ash or pro-V blades may be simpler (simply laminate wood together) but they still incorporate an AL sleeve as the blade/shaft mating surface. You could always try a simple wood shaft for the blade but I bet it would swell and contract when wet/dry. I'm guessing that's the main reason for the AL sleeve (plus a little more strength).
"If you dont do it this year, you will be one year older when you do"