To really enjoy knitting or crocheting, it helps to have the attitude of "Why would I buy x, when I can make it myself?" I'm sure this is often perplexing to non-crafters, and depending on what x is, it may appear to border on insanity.
For example, it's probably a little crazy to make cat toys. Really, it's also a little crazy to buy cat toys, since most cats I've known have been delighted by a crumple of paper, a bug, a reflection on the wall, or an imaginary (or maybe just invisible) beastie on the ceiling. This doesn't stop me, of course, from buying or making toys for the cats in my life.
My boyfriend's sister and her husband recently adopted a kitten, so to welcome the new cat-niece to the family, I sent them a few crocheted toys: two of the balls that Juniper loves, and a little fishy. And of course, to be fair, I had to make the same things for Juniper. Given how frequently her toys disappear under the couch, it doesn't hurt to have a large supply of them.
The balls are made with the same Ideal Crochet Sphere pattern that I used before, and the fish are Ana Rosa's Little Fish pattern. The yarn is random acrylic from my stash, and a few of the toys are stuffed with catnip tied inside a piece of muslin. They've been well received by both kitties, from what I hear!