I've found that when selling items that are valuable, but only to a few people, (i.e. vintage car parts) you need to list your item at a fixed price. If you have something special, don't be afraid to list it for top dollar. If it is worth XX amount of dollars to you, then it is probably worth at least XXX amount of dollars to somebody else.
Example: I had a xj6 dash in mint condition. I knew there was somebody out there willing to pay at least $400. So, I listed it at $400 buy it now. It sold within hours and I got numerous emails from people saying they would have paid twice that.
-Joe