The way we've handled it in the past is to standardize the prices for drinks and have members pre-pay for drinks. You could do two different colors, one for mixed drinks and one for beers. They get tickets (like you would get from a raffle), and then they turn them in for drinks. That way you can monitor how many drinks each person can be sold without having to worry about it there.
__________________
()---,, Nobody knows how happy I am!
|