Every week is ridiculous.
If they did implement the idea it would be better if once every 3-6 months. A superboss takes a long time to kill and if it is happening all the time then people are going to lose interest and so it'll take the ones who are trying even longer to kill them. Also when it became too devalued you would get less "rsvps" because it wouldn't be worth it. I don't think I could see people participating repeatedly after the first time they try and don't get anything either. Since they would be paying like 50m and spending hours fighting only to get nothing.
there comes my coin idea
everyone who participate (that means u have to be in the area until the boss is dead, like in union war, this could be one day ofc (sidenote: lol)) gets 1 coin;
if u collected enough coins u can exchange the coins with cool pvp stuff like rings and masks