What is my Harry Potter Lego Worth?

When I was younger (and still now to some extent) I was fascinated by Harry Potter lego. I own the majority of the 1st collection which was released in 2001 and 2002 and my collection is on-going. They include the Hogwarts, the forbidden corridor, Gringotts etc, everyone but the Hogwarts Express. Unfortunately, I only have the original box for the Hogwarts castle, however, I own all the original instructions and lego in excellent condition. I even have some from the next collection including Aragon in the forbidden forest, Dobby's release and the slytherine common room. All of these of discontinued now and worth a lot more than when I bought them for. How much would you say they are worth now and will they cost even more in the future?