So I couldn't resist anymore, I called to book the YMP package today. They sure had a lot of availability for Labor Day weekend! I was browsing the disneyworld website a few minutes after booking on the phone, and I found that I could've booked the special package on the website! I put in my dates and info and got the exact same quote. I've never been able to book any specials on their website before! Looks like the code on the website is YNW. Here's the link:
http://disneyworld.disney.go.com/wdw/special/offerDetail?id=AugSepMYWOfferPage
http://disneyworld.disney.go.com/wdw/special/offerDetail?id=AugSepMYWOfferPage