A few years back, I bought a few towels marked down at Target. I think they were $2 or less. Took them to Disney to use at the water parks.
We still have those towels and they are the "go to" towels for my DS 15.
Many places are starting to mark down summer items. If you don't want the towels taking up luggage space, buy a cheapie and leave it there. Besides, on another post, a DISer noticed a mom using a pool towel to clean a baby's bottom - ewww!