I don't know much about Chia Grass and have only seen it advertised, but would think that it is more expensive than buying normal cat grass, which is cheap.
As cats eat grass not just for nutritional reasons but also when they want to cleanse their systems because they are feeling under the weather. Its always a very good idea to give your cat or cats their very own grass patch, especially as if you don't, they will go in search of it anyway and could land up eating grass that has had chemicals or some other toxic substance sprayed on it.
If you have an indoor cat it is a very good idea to have some cat grass available for it to chew on and in some cases having it around, will help stop them from eating your plants, especially as that is not something you want them to do, just in case they take a liking to a plant that you didn't realize was toxic to cats. However as cats are picky creatures you may have to try a few different varieties of grass before you find the one that your cat likes the best
if you have more than one cat it is often a good idea to plant a grass mix, that way - they all have their different preferences catered for.
Catnip is a totally different thing entirely especially as it is not a grass but belongs to the mint family, but to cats - catnip is regarded as a recreational drug - as it has a euphoric effect similar to that of marijuana and you will often see cats pawing at it, stroking it or even drooling at the sight of it
I would say that as Chia Grass is just cat grass in a cute planter and that it would probably make a great present for someone who had cats, but would not be the best option for buying on a regular basis as it would make keeping your cats supplied with cat grass, much more expensive than it needs to be.
