Professional caterers can be expensive. Most will charge $10 or more per person for a simple hors d'oeuvre menu. A self-catered party will take a lot of time and work, but it could provide everything the guests want at a decent price.
Ask for RSVP's on the party invitations so you know exactly how many people plan to attend the party. Plan on making just enough food to serve that number.
Compile a list of all necessary non-food items, and determine how much it will cost to get them. These items will include decorations, rental costs if the party is not in your home, clean-up costs, plates, utensils, drinking cups and server pay. Consider every possible cost to form a total budget.
Plan a food budget to account for about four to six food items per person. Consult the recipes and package labels for the number of servings and divide the total by the number of expected guests. Plan on items that can be prepared or bought ahead of time.
Write a timetable of tasks at least two weeks ahead of the party. Pinpoint what will be purchased and when, and who is responsible for each item. Start shopping at least a week ahead of the party. You should have time to fulfill any last-minute needs that show up.