A $10 hour salary is close to $20k a year
Which means to make it worth it for him to bring in-house he would need to be getting back $40k from his claims.
$40k is only 4% of what his annual shipping charges are, so sounds like it shouldn't be hard to hit that number. Although, I have no idea what the "mistakes" stats are.
@Shmelly, you mind sharing the percentage ratio?