Collecting belt buckles is like collecting anything else. You look for condition above all else. There are many categories of buckles such as novelty, beer, truck and car, biker, rhinestone, and just about anything else you might be interested in. There are many good places to find vintage or new buckles on line. Here are a couple of belt buckles that I have for sale in my shop.
Find these beautiful belt buckles at http://goodneighborvintage.etsy.com/
Biker Buckle is Sold