TPU tools typically are pretty inexpensive for a component. Often with a heel piece they are the same part from left to right shoe, so there are some savings here as well.
With the Newson shoe, the mold had to fit the entire shoe, so it was quite large. To get all of the circles radiating in every direction, it was a 5 part mold, with a solid core. Duplicate that cost for the left and the right shoe, now duplicate that cost for each size of the shoe… $$$ Now make molds for the inserts as well that mechanically snap in…not sure what the dollars and cents were.