I'll give you the same advice I give anyone selling on craigslist or ebay. If it's not selling, it's too expensive. Yeah pictures might help, but people aren't going to buy a used wedding dress off craigslist for $750, in this case less than a 25% discount from what they'd pay at the store per your description. I mean, assuming the veil actually costs around $200 and the tiara is $50 they're only saving $100 versus going to a store where they can try on dozens of dresses and get them brand new.
People go to craigslist to get amazing deals. They don't care what you paid for it, what cleaning cost, or what sentimental value you've put on it. I've seen so many kitchenaid mixers on my local craigslist at 20% under retail, and they all stick around for months. You've got to put one at about 1/2 off for anyone to be interested. I messaged a guy about a toolbox a few months ago that he had listed for $50 more than amazon sells it for brand new, he said he paid $50 more than he was asking so that's what he needed to get for it. I'm sure if I went and looked it's still listed at that same price, and will be until he throws it away during a move or something. He couldn't comprehend that a brand new one from Amazon cost less than his, so nobody would ever buy it. To him he just couldn't bear to part with it for more than $50 less than he paid, so he expected someone to buy it for that because that's "fair" to him. That is not a seller's mindset.
If I was you I'd drop it $50-100 every week and see what happens. Once you get to the level that you'd rather keep it than sell it that low, just post it for $50 more than that and wait it out, or keep it.
Consignment is also an option as posted above. Not sure how much more you'll end up with once they take their cut but it's not a bad idea.
edit: And I'm not sure how alterations work, but if they're normally included for free by a shop when you buy a dress, that's an additional cost they'll have with yours (and thus an additional drop in price you'll need) vs a new one from a store.