I splurged recently on one of these belts: http://www.maxsui.com/
Very cute, but they are $40 apiece! I am dying to try making another one myself, but I can't find the buckle they use. It's a flat buckle, with a bar in the middle but no prong; the fabric has enough traction to keep it closed without a prong. Every buckle I've seen online has prongs. I don't really want to go the d-ring route with this project.
I also can't figure out what is the substance they covered with fabric to make the belt, and I'm not taking a $40 belt apart to find out! it's fairly thick, smooth, and flexible, like craft foam, but it's clearly more sturdy than that.