Alas! The only problem that I see with having a counter to show the number of sales made on the site is that it could lead potential users to believe that the rumors that nothing sells here are true. If such a counter does not show a steady increase in sales, it could backfire. So it could be something of a double edged sword.
Frankly, I've never been fond of the challenge to compare the site to eBay. Nor am I fond of displaying a total value of the items listed since such a figure is a meaningless estimate. In addition, I've never been fond of importing feedback from other sites since it gives a false impression of the actual history of the seller's activity on this site. Of course, even including imported feedback doesn't show those transactions where the other party doesn't leave feedback.
Naturally, there are more than the few items mentioned that sell here. Unfortunately, it is an impression that potential buyer's have gotten and so they fail to look on eBid for other things. Of course, seller's don't want to spend time listing if buyers aren't looking.
The specialization of the site might not be a bad thing. However, that would have to be determined and would probably limit the site's overall growth potential.
One thing that might be a bit more beneficial than the addition of a counter would be a reorganization of the category list. There isn't, in my opinion, anything worse than having a list of categories devoid of items in them.