The price of such a casserole is strongly determined by the material used as well as the size.
For example, enamel casseroles can be purchased at a reasonable price, whereas larger and more elaborately processed pots made of coated materials such as cast aluminium with a Teflon coating tend to be more expensive.
Compare several casseroles in different price ranges and set yourself a financial limit in advance.
As a rule, casseroles in the higher price range also have high-quality parts. However, this does not mean that a more expensive casserole dish is necessarily of a higher quality. In many cases, the manufacturer's name can also affect the price.