Bobby and Hanelize are amazing people and very skilled. They have a set of daily partners that get their attention because they send EVERYDAY not just when the cup runs over for some labs. The ability to service everyone in the manner they do is impossible and that's why they implement the booking system.
Finding the right person to outsource to is very difficult as you are finding, especially when you are looking for higher end designs. Many out in the market HAVE the skill but the need to get to the next crown which sometimes mean less than consistent results.
The asian market has a bunch of eager designers willing to work hard ( we get 3 to 4 emails a day) but the communication has been the hard part. For every artist you run across there are 10 more thinking they can use Ai and get the design to be acceptable. I gave up on finding one here.
Training in house has its own set of problems for the small lab, and in the end costs more in the short term. The time to take an average design and turn it into something better than average will always take more time than just redoing it. Having your trainee watch what you touch up or do is the best training in my experience it just sucks up a lot of time and that's generally what we do not have to expense in a small lab environment.
One suggestion, If you really want to be flooded with potential candidates post in either the Exocad or 3shape groups on FaceBook. These groups have designers from all over the world world, perhaps you will find a gem.
Good luck