I'm worried about diseases if the breeding pairs are coming from all over the place.
Have a conversation with them -- ask an open-ended question about the steps they follow while adding new birds to their aviary. If they automatically rhyme off those steps: which vet they go to, the tests they run, the quarantine period they observe, they way the quarantine spaces are physically separated, the biosecurity they follow to ensure they themselves don't cross contaminate during quarantine, the records they keep, etc... I'd take that as a good sign they've actually done it.
When I saw they sourced a pair from Italy and Holland (if I'm remembering that correctly?), my thought was, "oh, they're serious about doing something special here", and felt relieved they don't appear to be somebody whose birds accidentally had chicks and they thought it would be cool to sell them.
Another approach might be to ask Mark or Lisa at Exotic Wings in Saint Clements if they're aware of them (or simply see if they have what you're looking for), since they've been active in the area for many years.