Factors that affect the price of Olympic weights:
Material – Most Olympic weights for sale are made from cast iron. However, some of them are coated with rubber. Those coated with rubber tend to be more expensive
Grip holes – There are plates with unique cutouts at the edge that give you additional places to grip the weight and come with a higher price tag.
Weight precision and accuracy – In most cases, cheaper weights are usually poorly calibrated compared to expensive ones.