Verified answer

John, (or Hi John or Hello John)

Please supply me with the names of those you plan to bring to the event. I can then add all your names to the will-call list which will allow you to pay only ten dollars at the door, instead of the twelve dollars everyone else will be required to pay.

Hi John,

Could you give me the name of the people that you're going to bring to the event, so that I can put their names on the will call list. If your name is on the will call you only have to pay $10, instead of $12, at the door.

Mine may not be perfect grammar, but it is damn close. Hope I helped.