For a more elegant effect, you can consider printing black photos and hanging them using metallic clips on an interesting looking wire. You can do this by adding a neutral white photo canvas (in a digital processing computer program) like in the example above or by printing the photos as they come out of the camera. With minimum costs, as you can imagine. [costs: under $50]
In a hallway the photographs share black frames in different sizes. Despite their variation in size, the balance is achieved by the continual rotation from large to small in reverse and the fact the frames are positioned off of one straight center line.