You know someone that wants a set and willing to pay the going price or maybe a little less.
You have 3 blanks that you paid at most $1 each for. You have a computer and knock out the inlays in a few minutes.

Your cost to make the set maybe a total of $3.00.
You spend an hour or two putting the inlays on and putting the crosshatching on.
$3.00 plus 2 hours of your time at $15 per. Total invested $33.00 in labor and material.

Whats the going rate for a set?
What if you knew 2 guys that wanted a set?