In my experience most of the black tea that comes out of China has an overly strong floral note, more like dried loose-leaf tea rather than a "proper" cup of tea.... in fact I'm actually
vaping some DK Black Tea right now. Of course buying the flavoring is probably the easiest, you could probably infuse some black tea liquid with bergamot to simulate earl grey. I'm not too sure what the essential oils of the bergamot would do to an atomizer, but I've tried clove oil, and the atty seemed to handle it fine. As with other concentrated oils, getting that atty clean was a PITA, but good as an experiment.