From experience the domains do the selling not the market place.
+1 to that. If you follow the advise earlier in this thread and have a simple sales lander for all of your domains then anyone who might want to buy the name can get in touch with you.
If you already have that in place and are getting no enquiries at all, then that says more about your domains (or your pricing strategy, if you're displaying prices) than it does about the market.
Of course, you can always tweak and optimise the copy on the lander to try and get a bit more interest from those who type in the domains and land on it, but if nobody's typing the names in that means again that they're very unlikely to sell (i.e. demand = 0).
The problem with the domain name "market" is those holding portfolios of "good" names will not see any benefit from having their names diluted by being displayed alongside "poor" names belonging to other sellers. In other words, a hypothetical "unified sales platform" rewards the owners of bad names and penalises the owners of good names (since buyers can already access them directly via the sales landers) The incentives just aren't right, and never will be.
What might make sense is a registrar-driven initiative (or even a Nominet driven initiative) whereby the largest registrars club together on a MLS platform that would allow domain owners to "flag" their domains as being for sale, and that would automatically show up when somebody looked up the names on that registrar's site (via a Whois query or a search in a "register your domain" box) with a simple mechanism for the domain name to be purchased (and a commission remitted to the originating registrar).
But it makes no sense at all to push for a domainer-driven sales platform, because of the inherent contradiction between risk/reward I outlined above. That's incidentally the same contradiction that means that while Sedo has many millions of names listed, almost none of the "top" portfolio owners (as far as I'm aware) use Sedo!