When selling old gear, it helps to know its worth. Pricing too high gets you no buyers. And pricing too low means you're losing money.
Worth Monkey is a good site for checking gadget costs. Just enter the gadget you want to sell. The site will comb other sources to determine the current price.
You'll be able to select a competitive price quickly. It's also great if you're thinking of buying used gear. You can avoid overpriced items or haggle with private sellers.
Demo video: http://vimeo.com/14653613