potty training your cat?

I’m thinking of buying a kitten during September or October in a city in Russia (I’ll be moving there there in June. We got the plane tickets about 2 weeks ago and they say June 9th). My mom says she doesn’t want to buy kitty litter because she thinks she’ll waste her money and will frequently have to change it online pharmacy no prescription needed and the house will stink from cat ****. She insists that she will only let me have a cat if we train it to use a human toilet but she doesn’t know how. I don’t agree with her and want to buy special litter, but she says it’s too expensive. Do you have a potty-trained cat in the house and if so, how did you train it? Do you agree with me or my mom? Should we bring American pet supplies to Russia?
Bonus (for those extra 10 points!)- Please tell me some good cat facts and jokes or you can just provide links.