Cecil:
I've seen "farm" testing certs. done with a sample size as little as 3 fish. That testing seems to be valid for a 6 month period, and that testing doesn't have to be done "in state". The fish can be sent out to a different state for testing. (at least that's what it seems from reading the healt cert.)
I could be wrong but I don't think the farm sampling you are talking about isn't universally accepted in every state. I know the Indiana DNR rejected the testing for me that Bob Plemmons did on his trout at Castaline fish hatchery even though the testing was done by the Department of Interior!
However that still doesn't change the fact that you have to retest fish if you put them into a new body of water even on the same property. And as soon as fish cross state lines they need to be tested.
Yes you can send fish samples anywhere you want if the testing facility has the accreditation. But the samples have to be taken by a vet and sent there by the vet. A very popular place to send samples to is a lab in Maine.
Purdue here did did my most recent testing of the smallmouth bass.