Manage costs of a bachelor party trip

You're the best man and it's up to you to plan the bachelor party. Well, actually a bachelor party trip. You and some guys are kidnapping the groom a couple days before the wedding and going camping. You've got a great trip planned: hiking, canoing, rock climbing and a party on the beach to cap it off, but you need to get the other guys to chip in on the various supplies needed. Not all of the other guys are in town until the morning of, so you need an easy way to collect. Something that doesn't involve you paying up front and getting the money from them at a later date, because you know how that goes.