I did some peeking around, and considering that dress is selling/has sold-out at anywhere from $300 to $500 USD, I wouldn't want to buy one, either!
I feel like I've seen a retro or vintage pattern similar to that somewhere... I found one pattern that has potential for your project, V8615
, but with a narrower skirt, and you'd have to add a button placket. The DVF dress is pretty 40s-ish, with batwing sleeves. Looking at vintage pattern resources may be the route to go. Vintage Patterns Wikia
is a good resource, as they list known places to purchase given patterns.
Beyond that, I think you could start with a simple shift pattern and re-draft it into a v-back with a button placket. I found two from the Big 4 that might work if you don't find a vintage one that's closer, B5706
There's also several on BurdaStyle that could be useful, such as the free Candy Sundress
, the free Batwing Top
, and #111B
, which costs $5.40.
There are drafting resources all over the internet. Simply search for whatever you're trying to do, like "how to draft a batwing sleeve," "change shape of neckline on a sewing pattern," or "how to draft a button placket." Google search has been invaluable to me over the years
Best of luck with your project!