I didn't buy any and haven't needed them. Our cat was obsessed with the baby stuff before Austin was born, we kept having to kick him out of the moses basket/car seat/bouncer. When he was first born he didn't want anything to do with him.
At first we made sure that the door was shut if we weren't in the bedroom, and we were always in the same room as the baby, so there was no problem there. As Austin's got older we've relaxed a bit, we just move the baby stuff out of the living room at night. He's never once tried to get in the cot.
I'd put off buying them until you know you need them.