I would recommend Tyro.
My little sister in South Texas, my aunt and I have bought 8 BM's over the last 2 years. As I understand it, the "KK" strain is basically just a plant that originates out of Jon's Encanto Nursery. Somehow it got it's own special name. I've also seen people labeling another BM as "KK" as well. They sell it as being from "Portugal" - not sure about this either.
What I do know is our plants from the seller Tyro in California are incredibly healthy. They arrived in immaculate shape with thick dense wood and unmolested and have been vigorous.
The plants we have from whoever KK is are not vigorous and have all been pruned apparently before they arrived. This of course is limited to our own personal experience and not meant to discourage a purchase from that source. My little sister has 2 BMs the seller KK labels as originating from "Portugal", (which I assume he means is not Jon's strain from California) as well - one in ground and one that is in a 5 gallon bucket - both produce fruit that in our opinion is indistinguishable from all our BM's from different sources. - not particularly vigorous to note but again, BM is a slow grower.
Do your own research and if you can afford it I would buy a plant that has not been previously pruned and has put on 1st leaf growth already. These plants are tricky to grow - definitely not for novices like me. I have a couple family mentors teaching me the fig ropes or I'm sure I would've killed them all by now.
Should also note, my father prefers the Figo Preto strain as it seems to be the most vigorous with fruit that is indistinguishable from all the other BM's out there.
Cheers, Happy Growing!