£4.5k
I did a (crappy) sketch of what I wanted (I can't draw to save my life) and took it to a talented local dress designer who then made a proper drawing of the dress (taking lots into account I hadn't thought of).
That got jointly "finessed", then I picked my fabric.
She made up a tulle copy of the dress for fitting/pattern etc so we could make adjustments and when that was done she made the final version in silk.
Not cheap - but I got exactly what I wanted - and loved the whole process.
I had looked at pre-made dresses but couldn't find anything I liked at all - at any price.
Loads of strapless numbers or "princesses" dresses but I was channeling Mortitia Adams - no, not black (I went for a pale silver in the end) but think high collar with a deep v front, long draping sleeves and integral train.
After the wedding I took it back to her and had it altered again (taken to mid calf length and the sleeves made 3/4 sleeves).
I worn it about 20 times (to other weddings etc) and still love it.
Expensive yes - but I'm terms of price per wear probably a lot less than many other dresses.