You need to join the Connections program . A year membership is about $80, but you can do a 30 day trial for a $1. You can order them as soon as you sign up. Go to www.mousesavers.com to see info. on the program and for a link to the Connections website.
I would say do not buy them for e-bay. You will pay more and in turn would not save money. You may even end up paying more for the voucher than if you payed for the meal in cash ,depending on what the seller charges you for them.