To take that one step further, I’d let him pick, but so he has some skin in the game, tell him you’ll give him half of the savings if he chooses the lower cost option. That money, invested over time, has significant value for both of you.
We did that with our son, and he didn’t choose the cheaper option. It made the decision process interesting for him though. He didn’t make his final choice until 2 days before the deadline.