Look through my Trip Report (link at the bottom). If that is the one you see on DSO then YES it is the most amazing dress. It's a rich velvet and is wide at the bottom. It's one of my favorite dresses ever! One of my friends is listing all of her old dresses on ebay. I think theirs was a 5/6. She had this same one. It was a deluxe dress when it came out in '06. It's not real itchy. My DD wore hers for about 4-5 hours and never mumbled a word. She's usually sensitive to the itchy laces and decorations. The one from Disney is beautiful too but it's not that pretty!
Too funny- I followed the link to your trip report, and noticed that I had actually commented on your daughter's red Belle dress in your TR! I love your trip report- so many pictures. And this thread is fantastic!
Unfortunately, I don't think the dress I see on Disney Shopping is the same one your daughter has. It's on clearance for 19.99, but they only have XXS. I'll watch ebay. DD is 7, turns 9 in October, but she is very tall for her age and will likely need a size 10, since costumes usually run smaller than clothes.