The courtyard of the church is off the main port area and not obvious from the outside. Entrance to the church is free. When you enter the church, immediately on the left is a picture of Mary and Jesus surrounded by jewelry. I read that a number of miracles/good outcomes have been attributed to the picture and those who received a blessing, came back and left a piece of jewelry. There is a very small museum outside upstairs that costs 2 euros. As you peak your head through the door, you can just about see everything there is to see. I paid the 2 euros anyways, as I feel it is fine to give a donation.
Looking at the church and possibly the museum is worth it – it only takes a few minutes, both are small.