It just states a reasonable amount but I've heard people taking suitcases onboard. We just got off the Elation on Saturday. We had packed a small suitcase with Water, Pepsi and Root Beer. I figured we could use the suitcase on the way home for all of our great buys we find while in port. At the last minute as we were unloading the car in San Diego, we decided to leave the suitcase behind. I'm glad we did. They have water available on the Lido deck, at all bars and dining rooms. We bought a child's fountain card for my daughter. My son was happy with the free lemonade. I actually ended up only buying three cokes during the whole cruise. Sodas are 2.24 (1.95 + .29 gratuity added). They also have a big water bottles available in your cabin for 4.89. They also have coke, sprite and diet coke in your cabin if you wish to purchase. We never did purchase the coke inside the cabin but did buy the water.
To us it was much more convienient to buy then to lug the luggage from the car. Each person will need to determine how much they want to save money vs. hauling luggage.
Have fun...you will enjoy the Elation!
Say Good Day to Stu the Cruise Director (He is from Australia and he is a hoot)

Past Cruises:
1989 - Carnivale
2004 - Ecstasy
2008 - Elation
Next one...I hope sooner than later!