I seem to remember about 5-6 years ago a dealer who was back in the corner who would keep nothing on his table. When you went to him you asked for a specific category and he would take the book from behind the table and watch you as you looked through it. I can understand the security aspect but did not feel comfortable, so I did not buy anything. I don't think I have seen him since.

So short of every vendor having a CCTV (not really feasible)
Or every vendor having multiple helpers (again not feasible given the number tables/badges available)
Or every vendor locking up all inventory (I guess its feasible but not really a great solution)
Or increased floor security (dont think that will help much)
RFID tags (nope, not quite yet)
what can be done?

The cash is one thing - that should never be left on the floor or even in the open anywhere. And should of course be secured at the end of the day (I dont think that was a problem). But the inventory? Thats a tougher nut...