The eshop plugin for wordpress should be adapted for selling e-tickets.
When visitor pays by paypal, he gets immediatly his tickets (pdf) by mail or can download his tickets.
Tickets should mention in barcode a unique id (att: eshop makes only 1 id per order) the productname and option field.
When paying by cash/banktransfer, visitor recieves an invoice.
Admin section: when changing the order status to shiped the buyer gets an e-mail with the tickets or a message where he can download the tickets.
Admin has the possibility to send reminders to clients who did not pay yet.
Admin can print e-tickets per client.
admin can add tickets from backoffice and print ticket immedatly.
Download section, possibilty to download a file for controlling the e-tickets at the entrance.
Option: admin can select normal ticketing or e-ticketing.