PARK TICKETS:  For deals on park tickets:
By far, the most difficult item to find a deal on, unless you don't mind a time-share presentation!  

 

Visit our Disneyworld Park Ticket  page for current listings on Ebay.  Also, we have heard that the CD Walt Disney World Park Hopper Tickets & Passes Discount can provide deals on a wide range of things related to your DisneyWorld vacation.
 
We have also found Maple Leaf Tickets to be a great source for tickets (have used them personally and they were great).


OrlandoVacation offers a low price guarrantee on tickets

Tickets Disney World Vacations offers heavy Discount on Discount Disney world Tickets, Discount Disney theme Park Tickets

It may be worth it for maximizing your fun to get the Park Hopper option which adds ~$10/day to your ticket price.  If you stay at a Disney Resort Hotel, this allows you the flexibility to do early entry and stay late, which can add a lot of experience time to your visit (rather than waiting in lines).  Also consider using RideMax which really does increase your ride time by reducing your wait.  It is ~ $15 (one time, not per ticket, can be used by everyone in your party)