Another thing to consider is whether the pump is rated food safe. Bar bots are a very common project. You will find a lot of information on this topic with some searching. I remember reading the writeup for one that initially used windshield wiper fluid motors but they eventually had to replace them because the subject of whether the pump was polluting the drinks was brought up frequently. That's the last thing you want to hear when you're showing off your awesome creation at the party. Remember, alcohol is a solvent.
I saw one that used air (or maybe tanked CO2) to pressurize containers that held the drink components, which then forced the liquids through tubing.