If you plan on buying plants off e-bay, and I don't discourage that, I have got a few great deals from one of our better known nurseries on some neps, I would encourage you to buy off the scientific name, not the cultivar name, unless it really is a cultiver.
THis person looks like a con artist to me. As Purpera go, its a gorgeous specimen, but nothing special, and certainly not worthy of a cultivar name.