It actually isn't that hard to make your own set of planer (or jointer) blades. I haven't seen the DeWalt blades, but most of them are nothing more than a strip of tool steel with an angle ground on the edge. You can buy tool steel in flat ground bar stock in all different widths and thicknesses. As you buy it, it's in annealed state and easy to work. You can saw it to length with a hacksaw, and file or grind the bevel roughly to shape. Then have it hardened and ground by anyone who has a surface grinder or a Tool & Cutter grinder. You can even harden the blade yourself with a MAPP torch and a bucket of oil, and hand finish it with an oilstone. It's just a rectangular knife blade or a wide chisel.
If you have a grinding shop in town, like one that services printing companies, you can probably just give them the dimensions and they can make a set for you.