Clint, if you read the comments below the pictures on that site, you will see that HalleckHort states that it was developed and released by MSU and is being sold by Berry Nurseries under his Black Diamond trademark. Below that statement, Vossner says it had tags for both names, Ebony Flame and BD Best Red.
I would have to imagine that since the release was made this year (Feb/March) there may not any other nurseries with enough proven stock to start selling to the public...
I can not say why Black Diamond has so many to release. Anything said would be pure conjecture on my part. If you want a list of other growers, you have Dr. Pounders' e-mail address, and all you need do is request one.