I think you're right about the price tag, although after watching this review I will say I've gotten a lot more respect for the quality for the doll than I did when she was first announced.
My opinion that this doll is only $500 because she is limited to 500 hasn't really changed, though. Don't get me wrong, she looks BEAUTIFUL and I am very happy for anyone who wanted her and was able to get her, but minus the unique box design and maybe a small increase in production cost (probably for the veil and skirt of the dress, which are also my personal favorite features of the doll) there is nothing that really distinguishes her from any of the other LE dolls in terms of cost, fabrics, or overall appearance. This is even more noticeable with Blue Cinderella (because I'm willing to argue that her dress is just as gorgeous as Wedding Cinderella's any day of the week). One could make the same argument that she could have been priced $500 too...after looking at her box and the COA, not to mention the fabulous doll herself, I think it probably cost more to make her than the typical 17'' doll as well. But she is still the regular LE price plus $10 (for Lily James's royalties, as others have said). Why? Well, the only huge difference in quality/quantity between the two dolls is the edition size.
And all that said, I really don't think Disney will make a regular habit of making their LE dolls $500. They are still getting some backlash for raising the prices by $20 without any significant change in quality, after all, and Disney while hungry to make as much money as they can historically won't give up customer loyalty to do it. This Wedding Cinderella was probably just their way of making a Harrods-type doll (without the quality boost) for a special occasion; maybe they'll do it again if there is a Wedding Belle whenever Beauty and the Beast comes out, but I'm 99% sure that price won't show up for, say, the Aladdin dolls or other animated Disney characters down the road. And they tried to play it down, but they definitely heard a lot of complaining about the price not just from some of us but also non-collectors who just happened to read the announcement from FB or other places on social media.