What about making a player play to the end and only receive the contents of their box or only offered a deal when down to two box stage.During the game there can be swop's and still let the banker assume an amount that the contestant's are offered as a moneybuilder so that they can see it increase or diminish.
One big stipulation is no Partner's present although most say "play your own game" their body language shout's out deal and till you sit in that chair -believe me your better on your own,if the game doesn't go right for you there will be regrets for a long long time.

Happy debating or pick it to bit's