Strange how just adding that one additional day is increasing the cost of your rental so much more than mine. Still though, with all the insurance inclusions and extras, its a great deal even at the price you have now.
Our coupon is from the Entertainment Book.
http://orlando.entertainment.com/discount/browse.shtml
I would bet, though, that additional coupons will be released for August once the current ones expire.
I will keep my eyes open for coupons. You can combine a coupon and a corporate ID with National?
BTW - I noticed you are Canadian as well. We are in southwestern Ontario. Have you booked your flights?