The first thing that you need to do, is to do a financial assessment of the litter usage that your cat does in a month. This is because you will be calculating how much money you spend on your cat litter over the course of a month.
So what you need to do, is to add up the number of bags you buy per month, then add up the total cost that you spend on the cat litter. Now if this amount seems to be a little too high, then you should proceed to think about alternatives, if it is affordable for you, then you shouldn't mess around with your cat's routine.
Now the best alternative that you can have, is to go on and visit a construction site and pick up all the grey sand that they have. This is going to end up costing you close to nothing, simply because of the surplus amounts that they have available on the site.
The only difference that is going to occur, is that you are going to have to get rid of the sand more frequently, since it is not going to have the same absorbance as the other cat litter did.
The last thing for you to do, is to try two alternatives. The first alternative being one where you allow your cat to go out in the garden or the yard to take care of its business. This will see you spend no money on the litter at all, and is going to be ideal.
However, if you don't want your cat leaving the house, then you can opt to invest in a tool kit, which helps you teach your cat to use the toilet seat. This will also end up being rather cheap on the long run.