On package vacations, single travelers are often hit with a "single supplement" to the base price. To avoid it, you can agree to room with other single travelers or find a roommate before you go. Or travel independently: usually that will be the less expensive option and it will give you a better chance to meet the locals.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.