How to get my father to make end of life decisions?

My father is 88 with health issues. He thinks the "heirs" should make all funeral related decisions. The sample package he has been shown is over $12,000. If he survives 10 more years, this will be $20,000 based on the 5% increase a year reported by the funeral home. There are wide choices as far as caskets. If you make a decision now and pay for it, you incur no additional charges as your price is locked in. To make it worse he is considering cremation. I am + he should make that decision, cremation or not. His step sister and her husband chose cremation as a personal decision. My father failed to ask them why they made the choice. I'm sure his sister would have told him. He said "it was personal" I said, just because something is personal does not mean they won't tell anyone some of the details. His sister's daughter surely knows why they chose cremation. My father is too scared to ask her. I'm sure she would gladly tell him. Otherwise he is on his own. He keeps putting off discussions and if he waits too late, we may have to make the decisions and we might never agree on any of it. What can be done to pursuade my father to at least choose cremation or not. If you go the regular way, it seems the issue is how much do you want to pay. My opinion is make the whole thing as private as possible. I'd vote cremation. My sister would not.