Mail Order Dress Shirts

I am of Polish origin and I would like to bring something to a marriage that I reference, without being too outrageous. I do not think I would feel comfortable with the striped pants so that you see dancers wearing. I asked to wear a black caftan over a regular shirt and slacks. Can anyone give me advice or suggest where to find a supplier that does mail order?

Definatley regular black trousers and shoes. Then, wearing a white tank top and a kind of long sleeve shirts embroidery simple. I can not believe that they are called. Ebay is probably your best choice, or find a store near you. <Three