Parchment paper can be something of a baking miracle product. It is a high-density, non-stick baking paper that allows quick and easy baking with limited clean-up. That doesn't mean that it doesn't have any disadvantages. It carries a hefty price tag compared to its alternatives. For many applications, waxed paper, aluminium foil or silicon mats can serve the same purpose as parchment paper for a lower price.
Although waxed paper and parchment paper seem similar at first glance, they are actually substantially different products with different price tags and different uses. Parchment paper is a higher density paper lined with a special non-stick surface. Waxed paper is a lower density paper that uses a wax lining as a non-stick surface. Waxed paper cannot stand up to the heat of an oven and will smoke when exposed. This prevents it from being used for baking cookies or doing anything else in an oven where it is exposed. However, it can replace parchment paper in cases where it will be completely covered. For example, you can line a cake pan with waxed paper as long as the batter completely covers the paper.
Aluminium foil is another excellent alternative to parchment paper. Made from an aluminium alloy milled into a thin flexible sheet, aluminium foil can handle many situations that waxed paper cannot. Aluminium foil can be exposed to very high temperatures, allowing it to be exposed in an oven like parchment paper. Aluminium foil is also flexible enough to be folded into packets for packet cooking, much like parchment paper. Aluminium foil's primary drawback is in it's incompatibility with microwave ovens. Aluminium foil can not be used in a microwave because it is composed primarily of metal. Also, most aluminium foil is not non-stick, so it must be coated with a cooking spray before being used for baking, however some brands of aluminium foil feature non-stick coatings.
Parchment paper, waxed paper, and aluminium foil all suffer from a lack of re-usability. All of these products are designed to be used once then thrown away, resulting in a lot of waste and guaranteed repeated purchases. Silicon baking mats offer most of the advantages of parchment paper with none of the waste. Silicon baking mats are non-stick and designed to handle high oven temperatures, whether they are directly exposed to the heat or not. Silicon mats are also microwave safe. Because silicon mats are reusable, they must be cleaned after use. Clean-up is easy because the surfaces are non-stick, but it is still more time-consuming than simply throwing out old parchment paper. Additionally, silicon mats cannot be used for packet cooking like parchment paper or aluminium foil.