My 2p
I have never agreed with non members not being able to answer in the for sale section. A lot of engine / transmission parts sold are sought after by other car owners, who have absolutely no interest in kit cars. It's basically restricting the number of potential buyers. Would you pay to join say, the Allegro owners club to buy a steering column?
I can't imagine withholding the search facility will make non members put hands in pocket either. Apparently they can use Google, so what's the point. (In the real world, if someone asks you something about your Westfield, you don't tell him / her to f**k off join the club and do a search! Why should it be different on here?)
And, the number of threads recently rudely telling potential club members to "pay up or shut up" in my opinion, will have only one outcome. Potential club member goes elsewhere!