Eggs can not only be expensive, but also when trying to reduce a recipe meant for 4 - 8 down to single serving, they can be a nuisance to try to convert (you end up with weird quantities like 1/4 of an egg.)
The Cook's Thesaurus has several suggestions for ways to replace eggs in dishes. For baked goods, 2 tablespoons liquid + 2 tablespoons flour + ½ tablespoon shortening + ½ teaspoon baking powder works. For sauces and custards where the egg acts as a thickener, 1 tablespoon cornstarch plus 3 tablespoons water for each egg works well. And of course, these are a bit easier to reduce than a whole egg.