Have you considered Flippa?
http://www.flippa.com
I would be open to selling the company as its fully functional but haven't received any offers yet since it's low in traffic / not a huge amount of traction (~600 people have registered).
Saying "I developed a site, made some money on it, then sold it because I no longer had time" is much more impressive than "I developed a site, made some money on it, then shut it down because it wasn't successful enough."