We gave all ours away; there were loads of books. They went to a family who were putting their child through 11+. We didn't want any money for them. I think they are on their fourth round now. Some people sell theirs I think. There is nothing better than the act of charity especially when it comes to books.
We think that's a wonderful approach.
As far as selling books on the forum is concerned, we don't go out of our way to encourage this, and we do have restrictions in place:
Posts about the sale of second-hand items are not normally allowed. However, at the discretion of Moderators, an exception may be made in the case of long established members who wish to sell second-hand 11 plus material - but permission should be sought before posting. viewtopic.php?f=9&t=148