When buying cat toys, I've got two main criteria. First, it can't have any frills or gewgaws which the cat might be able to tear off and eat. Second, it won't hurt when I step on it in bare feet. With my current destructo-cats, there's a third condition stating the toy needs to be strong enough to survive more than one day. I once bought some yarn balls which they ripped apart overnight. Next morning it looked like a tribble exploded. I'm still finding bits of yarn whenever I vacuum under the bed.
For catnip toys, I usually get the ones which look like little pillows and are filled with catnip. Nice, simple, and the cats still have fun flinging them around.
Since my cats are large, I've never found an affordable scratching post for them, so I get the sisal (sp?) rope boards which are supposed to hang on a doorknob and just lay them on the floor. The cats like standing on them to scratch. Those come with little pouches of catnip to "season" the boards to get the cat interested. It seems to work, at least for my cats, though now they're trained to use the boards and I haven't seasoned the last couple.