UKC is technically "legit", they just do things differently than the AKC which, as I'm sure you know, is the usual standard for the US. With their asking prices being what they are ($1500 for pet-grade, $2000+ for show-grade) I would expect AKC titling. I wouldn't know anything about the DDBS since that's very definitely breed-specific.
Looking at the pedigree for Amador, it looks like he's double-registered which is nice, but it only works one way (AKC doesn't recognize UKC, but UKC recognizes AKC). Looks like I was mistaken earlier when I said they don't use AKC registered dogs, so I apologize for that, but since they only show in UKC that raises some flags right there. Better than seeing a pedigree full of CKC registrations, at least.
DD raises an excellent point - we can give you all the opinions you can handle but at the end of the day it's your dog. The breeder definitely doesn't appear to be a BYB or mill and the animals look pretty healthy so if you're comfortable with the breeder and her dogs and the contract/price and won't be showing AKC anyway then maybe all that doesn't matter. If you like the look of the dogs, then don't let us stop you LOL. Would you be getting their available female pup or putting in for the December Atticus/Apple litter?
~Marrow