We make frozen "bucket" margaritas in our room and then fill our large plastic glasses and take those to the pool. Way too expensive for pool drinks at $7 each.
We packed large insulated cool cups (got them on a cruise and they weight little).
Bought a bottle of Sangria, a bottle of mudslide (pour over ice type) and a bottle of rum along with fruit juices to make rum punch... No, no, we were there two weeks, it's not that bad.
We also bought 3 cheap ice trays and ice tub for our freezer (worth the total $4) so we'd have plenty of ice.
We had great adult beverages by the pool every day this way at a fraction of the pool bar cost!