My wife has the traditional thumb slugs, she just decided to go from 10 pound to 13 pound balls as her shoulder finally healed from surgery, the guy running our pro-shop was able to take out her slugs and finger tip inserts and put them in the new balls, that's where my thinking came from.

But even still, the drilling is the main cost, and could be replicated even if you can't get the slug out, or it is too worn down. In her case she only had them put in back in February, so somewhat minimal use to this point on them.