Tacky or Not???

MOH and I were talking about games at the bridal shower. She wants to place a mason jar filled with m&m's and have guest guess how many. I was like ok that sounds fine, then she was like yeah they would get 3 guesses for a buck. I was like hold up nope stop. I think that its very tacky, to invite people to a bridal shower ( who you kinda are expecting a gift from) to pay to play a game. She tried to spin it that it would be there choice, and that if you get some people that like to gamble, then you could really make something of it. I am against this, and she brought up the dollar dance at the wedding, which i explained to her is a common thing in our area ( this is the first wedding she will be going to, or a MOH in) Am I wrong that i think this is tacky about asking people for money at the bridal shower, even if its a voluntarily thing???