I've recently suggested we close the following question:
I've given my reasons in the comments. They are (I believe) broadly in line with the policy on shopping questions on other SE sites. Indeed, I'm even not sure that it is a question that applies specifically to LEGO - I could ask the same question about other things (Action Man figures, Comics, etc.)
Joubarc, for one, sees merit in the question, and I can see his point - there does seem to be value in providing a comprehensive list of places to obtain old LEGO. Moreover, we already have numerous questions tagged shopping, and to be honest, most (if not all) of these seem to fit well within the scope of this site.
The other thing that bothers me is that questions that promote list-style answers and "requests for resources" have also frowned upon elsewhere on SE... but I'm not sure that the "rules" have always been applied in a sensible way, nor that they should apply to this site in particular. There are already several questions whose answers are lists, and questions whose answers provide external resources. To me, the seem perfectly fine - indeed, I may even have contributed to some of them. In my opinion, then, they provide value to the site, and I'd be sad to see them go.
So, my question: as a site, what is our policy on shopping questions? Assuming we allow them, how can we differentiate the good from the inappropriate?