I've been surprised by the lack of success I've found on Still White and similar sites given the pricing and condition of my gown, and I happen to be on a timeline to move.
Despite the estimators of sites like these, which suggested my brand new gown would be worth about 60% of its original price, it doesn't seem that the resale market will actually bear anything close those valuations, which is the true value of anything, afterall.
It was brought to my attention that, should I donate the dress to charity before the end of the year, it would likely be worth more to me as a tax deduction than the price for which I can legitimately sell it. (Note: I'm in the U.S.)
It hadn't even occurred to me, so I thought I'd share in case anyone else found it a useful idea.