Not sure on reputable breeders. We recently put a deposit in with a Bernedoodle breeder, but before we found them we joined a Pets in Montana facebook group to find a rescue or puppy. Holy crap. The number of what I assume are accidental puppy litters and backyard breeders is insane. It seems like legit breeders do post in there at times as well, but it can be hard to tell unless the person's page has a link or says they are a breeder. Lyon Labs posted 2 days ago that they have male puppies still available, 4 weeks old. However, I have no idea if they are legit. No website, just facebook.
I looked online at a bunch of breeder sites and talked to the breeder we are getting from. They have a website and a facebook with a fair amount of good reviews. After a decent length conversation we decided to go with them. Should get to pick our pup up in a month.