I love collecting various metal racks. Their original purpose is for holding plates, kitchen utensils, photos and such. But I found that they are great for holding prints and other art materials.
Even more exciting is that due to their straight backs they are easy to hang in booths and on art boards. This gives the display more dimension making it more interesting. All of these racks were under $11. The silver one is from IKEA and costs about $4. It's perfect for card displays or promotional material.
You can add more prints, cards or promotional fliers to your walls without them appearing overwhelming.