We just bought our wood caps (like angle iron but with a third edge) from Country Manufacturing. I didn't price the angle iron/corner guards, but the pieces we bought were about $10 or so a piece cheaper than Woodstar with free shipping so that's why we bought from there. I'd trust Woodstar as well though.
We had the local furnace company bend some galvanized sheet metal, to cover some boards. Just wrapped them up to protect the wood. Our covers were for wood hay manger edges. Worked very well, screwed on with washers under the screw heads. Lasted about 20 years! No scalloped edging anyplace!! Told them what the dimensions were, everything fit just fine. Metal was light and easy to work with, though cut ends could be sharp, so wear gloves.
If you use any of the angle iron or sharp corner edgings, DO GRIND off the sharpest point edges. That sharp long edge can make a split in the skin easily, just with impact of horse on metal. Doesn't take long with a metal grinder, to round the corner on the angle iron. Wear eye protection and gloves for flying sparks. Probably should be ground off before the angle is mounted in the barn, because of the sparks flying around.
Get some width to the angle sides. Some very bored horses will go on a mission to destroy your facilities. They can dig out the wood just past the metal edging, if metal is shallow. I think our window ledge angle is almost 3" from the metal corner. Covers more wood, no place to grab and gouge out the wood behind the metal.