I bought the jacket from another german cosplayer, who sewed it herself. I added the missing waistcoat which I sewed myself and added none-self sewed white trousers, a blood red tie and the black shirt. And I bought the juwelery. restyled a wig I bought by mistake for me. But there are really good Night class suites on sale too, if you can't sew.
I understand what you mean. It's hard to come up with a good background idea for me, too. But in the case of "Dragon Promise" I had a vision, how the pic has to be, so I simply tried to draw the pic I already had in my mind.