This makes no sense to me. If it's really possible to "resell these domains for considerable profit" then why aren't you doing it yourself? Or, if it's not, then surely you're just preying on the greed and gullibility of those who sign up?
I wish I could sell domains full time, but I have other commitments. It takes time to market and promote domains and sales don't exactly happen over night.
There are sample domains shown on the signup page. I think it's fairly obvious good keywords and brands are worth more than $19. It's not so far fetched to think someone could resell for much more.