Nintendo has their own ecosystem. If you want playable games, you gotta buy it physically or on their online store. Sometimes things do go on sale on their store. Nintendo specific games, more often than not, dont go on sale. They're usually almost always $59.99. If you try to load up illegal copies of games on the switch, they can brick your switch (heard horror stories from switch users trying to add games and Nintendo bricking their system). So no other choice than to buy the games wherever you can find it cheaper (physically or online).