The magnets from United Nuclear have shipped.
An article by Shannon Larratt mentions an individual who has a custom titanium encapsulated magnet. This could also be a direction to look in to. According to him, the implant has not resulted in complications, but he has reported it losing sensation. He also mentions the purchase of special Syringe used to implant RFID tags into pets, which may be much less invasive than scalpel and pocket implantation method.
As far as Parylene coating services...
Apparently coating a single magnet at a time is not very practical, but magnetized magnets would most certainly stick to each other resulting in an unsuccessful coating. Some have the facilities to produce unmagnetized magnets then coat and magnetize them, others can coat magnetized magnets. Some can't handle magnets at all.
It was suggested at some point by one company to demagnetize, coat, then remagnetize the magnets. A conversation with a coating company today led me to believe that demagnetizing a powerful magnet would permanently damage its structure.
...So that idea is out the window for now.
So far of the companies I have contacted:
Three companies I have contacted have responded with estimates, another has promised one by email.
One company has said they are incapable of doing it.
The rest have not responded to my request for information.