I'd suggest scouring the internet . There is birdbreeders.com, and I fail to remember any more off the top of my head, but there are many websites out there that list bird breeders.
If it's in the pet trade (which it is) you should be able to find it somewhere in the US Remember, some breeders advertise more far and wide than others though, and that can make it harder. I got lucky when my otherwise hard to find Ruppell's parrot was right in my town, but my BW Pionus is not as rare (but like the Wagler's conure that you're after, a bit obscure and not a super high demand), but nonetheless, though it took me searching off and on for a couple years to find a good breeder with chicks, I found Raven. But I was determined . Good luck.