XF 1.2 Limit Number of Searches for Guests?



I want to be able to encourage registration by limiting the number of searches a guest can perform. I found this very effective in VB but cannot see an option in my XF Admin settings.

If I turn search off to guests many people drop off without reading site content, whereas if I allow search point blank I have less to sell them on to join the community.

I would love to hear what others offer members for joining too?

Of course this is not the only benefit of being a member, but I found it to be the most enticing.