Purchasing alcohol in Miami

[Catperson]

We will be on the NOS next December for our first cruise and will be flying in to Miami the day before our cruise. We are planning to stay near the port for the night. Is there a liquor store/convenience store close by so we can purchase alcohol/mix/water for our cabin. The bottles/cans are obviously too heavy to be lugging onto the plane so we thought buying near the port would be a good idea. We just like to have a little something for our balcony.