Very neat! I had never thought about what's inside a waffle cooker.
I know that you can buy dryer heating elements and cut them to length. Another option could be to buy a small space heater and cannibalize the nichrome coils from it.
The waffle cooker should have a wattage rating on it. You'll need to cut the new element to the correct length to draw the same wattage as the original one. Then, spread or compress the coils to get it to fit in the holder.