My father does not understand the importance of a grinder!

My father wants cafe quality coffee at home (who doesn't?) but is not willing to buy a grinder. There is a aeropress, french press and a flair neo flex at home and he asks, "shall we buy equipment for a v60?".

I have told him multiple times that a grinder is the most important component to coffee grinding. Since we can get grinders from the US, I've suggested the kingrinder k6 (he doesn't want it because it is too much effort) and even electric grinders like the baratza encore esp (he says it has too much plastic and wants metal grinders)

Today I finally told him that the grinder is very important and that we should buy one, and he says "find one under 100 USD", to which I replied we can buy the kingrinder k6. He said "if it's a manual grinder it should be under 50 USD since we are doing all the work".

Can someone please tell me how I can explain the importance of a grinder to him?