In addition to the World of
Disney Store at DTD/DS, the store in DHS on the right side at the end of Sunset Blvd. (can't remember the name of it) and Uptown Jewelers in MK, I believe some or all of the Deluxe resorts sell them in the gift shops. I know I've seen them at a few resorts but I can't remember specifically which ones -- though I'm pretty sure I saw them at Grand Floridian. The problem with just going to one place to buy a bag is that the won't all necessarily have the same patterns. When we were there in June, I only saw the Haunted Mansion bags at Uptown Jewelers. I usually look at Uptown Jewelers, World of Disney, and the shop at DHS throughout the week and then on our last day I go back to the store that has the bag I decided to buy on that trip.
The promo isn't good on Dooney & Bourke bags
But I did get the Disney Visa Discount (10%) on the D&B Haunted Mansion bag at Uptown Jewelers when we were there in June.