Here's how that $33 bill might have been itemized:

$1 - materials
$4 - labor
$3 - overhead (rent, insurance, etc)
$25 - knowing which spokes to tighten/loosen and by how much

30+ years ago a bike shop owner confided to me that he knew he generated one future wheel truing job for every two spoke wrenches he sold. He sold them for a quarter but added he would have given them away for free if he were not afraid the customers would catch on.

Wheel building/truing takes practice. Buy that spoke wrench. However, get yourself a junk wheel on which to practice.