You'd be surprised how many kids DEMAND that they be given one due to the terms of: "You have too many".
Couple days ago a girl came to the quest lobby and went bonkers because she was convinced she entered a kiosk give away room.
Posters above pretty much covered it all.
Kiosks can't be traded
Quest magic/items (purple super suit), kelloggs magic, and gender items can't be traded
Quests can be hosted for whatever amount of credits a host puts in it.. if it becomes a popular and more public way of trading, we can bet we'll see a limit on how many credits can be won