According to the OP, he is giving them away, not looking to sell them, so it looks like he is trying to be generous. I have gifted them to friends and family a couple times when I didn't end up using them. I just recently downgraded to the blue card because the Alaska pass was just way less restrictive and easier to use.
Back to the OP, the only thing you can do I think is either trust the other party or have the other party trust you. Because either you will have to front the CC charge initially when you buy, or they will have to give you their CC info.