Cats can usually find a toy to play with whether it’s a piece of string or your valuable laptop computer. However, if you feel your cat still needs a toy, you might consider buying a cheap one just in case your cat decides to ignore it.
For less than $10, you can get a bag full of catnip filled fake mice for your cat to bat around and stalk. For that same amount, you can also get a bunch of random cat toys such as balls with bells in them or crinkle toys that cats seem to enjoy attacking.
So consider spending yet even more money to keep your cat amused, even though it will likely just attack your feet and hands and ignore any new toys you buy them anyway.