I'm a bit confused here. Is that your website or do you want to start a similar website?
He wants an service with an API that lets him sell virtual credit cards, just like the website above does. Basically, putting another middleware in the "customer <> vcc seller" process, making the user pay even more fees for nothing. In the website above, you already pay up to double the amount of the card to get one (e.g $13 for a $5 card or $133 for a $100 card), so I don't see anything using this type of services. And if OP can't even do some research to find a provider, I don't see him having a successful website.