Ebay

Mountain bikes
When is a Mountain Bike 'Too Old' to Justify Buying?
  18
MTB Tips
How to Buy a Used Bike Online: A Practical Guide
Mountain Bike Podcast
The Singletracks Team Talks Santa Cruz Bronson, Selling Bikes Online, and $80 Helmet Cameras [Podcast #9]
MTB Tips
How To Sell Your Bike Online: A Practical Guide
  4