The cheapest way to park your car in Amsterdam is parking at one of the MobiHub P+R locations on the outskirts of the city, and travel into town by bicycle or public transport.
If you still need to get to the city centre by car, you could park your car just on the street or in a parking garage.
Parking rates for street parking vary from €1.40 to €7.50 (in the city centre). Almost everywhere in Amsterdam you have to pay to park your car.