Know whether it will be safe to walk from your hotel to where you will be going. If you plan to rent a boat or Jet Ski, add that to your budget. For hotels, your best bet is to use an online travel company for the least expensive rates, or check newspaper ads. Be aware that some hotels in spring break destinations do not take students during that period due to bad experiences. Another way to save money is to share a room.
Many properties offer triple and quadruple occupancy.
It doesn't pay to sneak more people in than the property allows. The management probably has seen it all before. Consider a youth hostel. While these are for people of all ages, the prices are low. You might have a curfew or have to do chores to stay there.