Ask around your hometown for classmates who may own bars, restaurants, hotels or other potential reunion venues. These people may be more than willing to offer a good deal for their own reunion. Scour the area for the best deal. Many bars have large rooms available for a minimal fee. Consider a casual picnic at a park or beach.
Parks offer room to eat and drink, play games, socialize and lounge very inexpensively.
Ask for special group or event rates, and include the hotel information in the reunion invitation. Think about approaching the school's administration offices to see if you can use the school's gymnasium or outdoor recreation area. Nostalgia will run rampant when alumni show up to party at their very own alma mater. Research caterers in the area to get the best price for large functions. Collect modern CDs as well as favorites from your school years.