If the embroidery was done by hand, the cost would shoot up fast (even if the materials were low quality).    Also it looks like they had to alter the style heavily (heh) to fit the bride, and alterations for heavily embellished gowns are $$$$$$$$$. edited to add: I really don't think this is the same dress.  The designer's name isn't mentioned anywhere. It looks like the original dress was £175k and this is a copy.