I rarely post anything for sale or trade on this site. I have a group of members that I either know personally or have a long history with and tend to avoid people/transactions where I am unsure of the other party. In the past, I got burned on a few transactions and felt taken advantage of so now, I just sell my junk on ebay or give it away. I agree with RFC, if you need to try and haggle with me on a $15 part, maybe you should focus your attention on more important areas of you life.
All that said there are also many, many, generous, nice & genuinely caring people who hang out on this site. I just want to keep it that way so I actively avoid commerce here.