Pam; Personally speaking, I don't put any added value on a blank card. Sometimes the blank cards are more plentiful than cards that have been issued to a player. The A.C. Sharks card is a prime example. If somebody knows somebody in a casino, they can get a sizeable quantity of any card manufactured. Quite a different story to find the same card(s) that have been left behind or "orphaned" by a player.

As for numbers, prefixes, letters, position, embossing, etc. My own personal collecting position taken is that if something is added (printed) to the card at the casino ... I don't consider it to be a different card or a variation. If something is different on the card that was done by the manufacturer, then I consider it a variation. I know some folks collect differently, but that's how I see it.