How should I make a realistic rendering if I haven't seen the case in reality as well? I could only imagine and make guesses how it would look like, but then again, if it looks different, people will complain. So a photo makes more sense. Anyone will be able to imagine the final product as good as I can.
OK, but can you share what's going to be different and what's staying the same ? It's just really hard to imagine without any description. And I think it's ok to put renders and clearly indicate that "render only, final product look and quality may differ" since that's what most industries do anyway.
Without any of these details, it's a big "leap of faith" to put 130+ euros on the table without knowing much about what we can get in the end.