I wish there was. I don't know what good a certification would do anyways.
Now, it seems a reputation is developed by experience with picky customers. How do you get the experience without having a reputation? Work under a known smith and then strike out on your own.
The guys who take a shortcut with this do seem to suffer.
Tippie tried to turn a shooting skill into a smithing skill. Didn't happen. I recall a post he authored, blaming a premium barrel maker for shattering his solid pilot reamer. The barrel maker was known for tight barrels, and I recall he did not seem to grasp how to fit a pilot to a particular sized bore. That post should have been a huge red flag the guy was in over his head.
Other guys seem to realize their limitations and make parts, or do simple work that does not tax their expertise or equipment. Some of the names around here got started only 2-4 years ago.