Before deciding to buy a copper tub answer the question. Are you familiar with copper patina? Is good to know that copper in a process of oxidation turns green and I doubt it is what you as a buyer want it to look like unless it is a part of the bathroom design overall.  There are ways of making copper tub darker, lighter or antique looking and then sealing the surface making it permanent. On product pages of you will find five options including natural copper, honey, coffee, antique as well as green.