Buy some coin magnets (square or round). The kind you find on refrigerator magnets. Buy some 3M peel and stick mounts. They come in a wide variety of shapes and sizes, available at every hardware or craft supply store.
Put one coin magnet on the outside of the print, another right behind it, on all 4 corners. Put the peel-n-sticks on the back side magnets. Press and stick on wall. Magnets reusable, peel-n-stick not, but cheap. I've used peel-n-sticks on all types of surfaces - plaster, wood, stone, metal - and removed all with no problem.