I've read so much about having a collapsable cooler on board for various reasons. I've read about purchasing them onboard and then you've got a souvie to take off the ship with you and I've read about some of the great deals some of you have gotten on coolers at Costco, etc. So, my question is this: which do you recommend and why? Bring your own on board with you (we're driving down) or purchase one once on the ship? Thanks for your responses!