The GM can sell you a ticket from their part of the App. on the spot (as it were). They have a "Issue Ticket" button on their event display. They should know about it (it's in their EO/GM FAQ), but you can point it out to them if they've forgotten.
Their instructions say (in part):
- Enter the username of the potential ticket recipient. The username is associated with their Gen Con Account.
- The attendee must be signed into their Gen Con Account.
- Once the ticket has been issued, the ticket will appear in their cart and an email notification sent.
- The attendee must complete the purchase before the ticket expires from their cart.
- If you don’t see their name listed under Ticket Holders for the event, they have not completed the process.
- Remember they must “Give ticket to event host” as well.
Gen Con, LLC.