When buying any work of art, it helps to hear from an expert what you should be looking for – and a $15,000 or $500 action figure is no exception. So ahead of Sotheby's upcoming Star Wars-dedicated auction Return of the NIGO, we spoke with several of the foremost authorities (and fans) of Star Wars collectibles, including Gus Lopez, creator of the website Star Wars Collector's Archive, Jordan Hembrough, a professional toy dealer and television host for Discovery Channel and Quest TV, and Stephen J. Sansweet, chairman and president of Rancho Obi-Wan, a nonprofit museum that houses the world's largest collection of Star Wars memorabilia. Click ahead for their top tips and trends for seasoned and budding collectors.