How much would it cost for someone to ask someone to marry them on a jumbo tron?

I don’t know, but if it is not the other person’s idea to get married, it could get ugly. Someone just run out of there instead of the expected reaction

I would guess that it varies from location to location. Tell him to call the venue and ask them.

To do this at Joe Louis Arena in Detroit, during a Red Wings home game, it’s a $250 donation to the Red Wings Wish Club (a children’s charity). Link. I had to look this up for something a while back, you might want to check the venue you have in mind for what it would cost there.

If it’s at the Yankees Stadium, it’s $500 according to this video