No discounts I know of unless you want to do a timeshare presentation to get them for free (UGHH!)
You can purchase them in advance at disneyworld.com but you will pay a fee to have them shipped to you. You can also order and then pick them up at will call when you arrive.
Finally, there are a number of ticket kiosks at the parks where you can purchase your ticket using a credit/debit card. No need to stand in line at a ticket window.