This is an interesting twist on the standard dinner fundraiser that can prove very entertaining if done correctly. Tell everyone coming to bring along an individual serving, cooked meal or dessert, their checkbook, and their sense of fun — the trick is they will all be bidding for their dinner.
The meals provided can be as straightforward as hard-boiled egg or scrambled eggs, or something much more towards the elaborate end of the scale like lobster thermidor. It's up to each of your guests to decide what to bring along. Cover each meal (keeping hot meals in a warmer where appropriate) so the participants can't see what they are bidding on, and let the process begin.
You have the option of starting the bidding at the same point for each meal, or beginning with a high or low bid to keep guests guessing as to the quality of the meal. If you think it will drive the price up (and raise more funds as a result) you might want to reveal some of the meals during the bidding process. You might find a peanut butter sandwich going for $25 and a prime rib steak selling for $5. Just be sure to check for any potential food allergies before the bidding process starts.