There is no charge to enter Vatican City, however most of the city is not open to the public. St. Peter's Square and St. Peter's Basilica are open to the public and free.

The Vatican Museum does offer tours, however these must be booked at least one week in advance. The Museum and Sistine Chapel tour is € 21 Euro. The Vatican Garden Tour (one of the only ways to get behind the walls of the city) is € 13.50.

Tickets for the museum and Sistine Chapel without a tour are € 12 and are available at the door.

…vatican.va/3_EN/…MV_Info_Servizi_Visite.html

Personally, I dislike tour groups. I dislike being rushed along and I prefer being able to browse where and when I want. However for the museum and gardens, I would book the official Vatican tour simply because the gardens are not accessible without a tour.

The Vatican also offers a wonderful gem called the Scavi Tour. It gives a tour on the escavations under St. Peter's Basilica near the Tomb of St. Peter. I do not remember the exact cost of the tour, but it is minimal.

Here is the website of the Scavi Office.

vatican.va/roman_curia/institutions_connecte…

Enjoy your trip, Vatican City is a beautiful and fascinating place full of hidden treasures.