If this update were to exist, I would probably set a wager cap at 1000. The real issue is that how could you get two sparers to wager the same amount? Maybe go with the lower amount wagered, so the player who bet more wouldn't get ripped off.
This would also have to be in the mixed room only, since you could easily boost your money with noob accounts otherwise.
Questions: would you be betting against someone, or betting that you'll win your next match?