This doesn't seem particularly advantageous for the consumer. Here in the States, you pay about the same amount for private banking, and you get the entire sample to yourself. As someone on this thread already noted, there isn't that much blood per sample, even if it can be taken (which sometimes it can't be, for technical reasons). Why is this Virgin model better? I don't see it.
I'm not sure if sample size will remain a problem in the future as the various growth factors are characterized and understood.