Entropay is one of the best websites in where you can get those virtual credit cards without any fees. But wirex works fine too, and uphold too, there are a lot of websites that are offering this kind of services in where you can load your vcc with bitcoin funds, or just with paypal funds too, i dont know what are you trying to do since i dont know digital ocean at all.
But wirex works in most of the websites, it should be fine, take a look on that card provider.