I think this is a great post/question. The one comment about subscriptions not being allowed seems to ring a bell, but it's too bad if that is the case.
I would also second the person who says they don't want to pay for the gamble, I want to know what I am getting so give me a $200 character rather than make me open packs with terrible odds hoping for a winning ticket.
As for other possibilities, a few that I might pay for are:
-ability to trade in old gear. If I could pay money to get access to a shop that converts unneeded stuff into useful stuff, I'd be all over that.
-I might occasionally pay for a "redo" in grand arena. Say I feel like my team got horrible RNG and I really want to give it another shot. I'd totally pay $2 for that. Would have to cap it at 1 redo per event though. Kind of like a mulligan.