I've never stayed at the Sheraton, so I can't offer any advice.
But, I'd be interested in the "awesome deal" you found if you were willing to share the details.
Yeah, it sort of was weird!
There may be an easier method, but this is what I did: First I went to Trivago and searched for Tokyo Disney Resort for my dates; I pulled up the "deals" for Sheraton, and clicked on the link for Priceline, which actually wasn't the cheapest one (would say something like $240). But when the Priceline site opened, it remembered me from a previous sign-in and offered me a 15% off rate, which was $142 with free cancellation up until a couple days before the reservation. I have a rental car booked with Priceline but it is a totally different trip (1-day in Florida in February), but somehow that triggered the 15% savings! I booked and paid (prepaid the whole amount), and actually went back in today and it was $10 cheaper per night, so I rebooked and cancelled my previous reservations without penalty (another weird glitch, when I went to cancel it, the site said I'd have a HUGE penalty, like 10x the actual reservation cost; but I contacted Priceline directly and they said it was a web display glitch and my reservation was definitely free cancellation, so it would be safe to do so)!
The room offers I got were:
Stay 1: Oct 27-30 (Sun-Wed)
-$133/night for main building
-$142/night for park wing
-$142/night for ocean dream
Stay 2: Nov 4-10 (Tues-Sun)
-$152/night for main building
Weird thing was too, if I just went to priceline directly and signed in, it didn't give me the 15% discount, just if I went thru Trivago! Hey, I'll take whatever discount I can get!