Personally I think if you offer a domain to sale to an end-user, you are at an immediate negotiating disadvantage. One thing I tried was to go to the website of a prospective buyer, find a bug or typo and send a friendly email to them saying "by the way you have an error..." from the email address of mydomain with a signature.
I didn't sell it (yet - this was only 2 weeks ago) but i did see from my logs that they clicked through to the site - twice - , so they are now aware it exists. The site has a message on it suggesting that the domain is no longer being used too, but not actually offering it for sale
