Have a potluck meal, where the guests bring the food. This can be the ultimate DIY: no cost or cooking for you. Consider the guest experience as well. Not all of your guests will be enthused at the prospect of bringing their own food to a wedding. So add a quirky twist. For example, make it fun by having a cooking competition or other food-centric event; have them bring food in lieu of a gift; or make it a recipe exchange.
This tip is based on an excerpt from the Dream Wedding on a Dime; 7 Secrets for the Budget-Savvy Bride ebook.