Yes, if you are purchasing a drink it can be quite expensive unless you are at one of the highly-advertised $1/beer places. If you are playing a machine or table your drinks will be "free" ... just take care of your waitress with $1 per beverage (beer, water, whatever). If you sit at a bar to play their machines, you might want to ask if they have complimentary drinks. Some places will require you to play a certain amount at the machine and then won't charge you. I always ask (even though I risk sounding dorky) before I start playing and/or place an order.
Note: Upon placing your order with the waitress, please get your tip money out! It is very bad Karma to not tip your waitress and she doesn't have all day to stand there while you fish out money! LOL.