ProductPrice.cs

public class Product : Entity, IAggregateRoot
{
    public string Name { get; private set; }
    public decimal Price { get; private set; }

    public Product(string name, decimal price)
    {
        Name = name;
        Price = price;
    }

    public void SetName(string name)
    {
        Name = name;
    }

    public void SetPrice(ProductPrice price)
    {
        Price = price;
    }
}

public record struct ProductPrice
{
    private readonly decimal _value;

    public ProductPrice(decimal value)
    {
        if (value <= 0)
        {
            throw new DomainException("Product price must be greater than zero.");
        }

        _value = value;
    }

    public static implicit operator decimal(ProductPrice price)
    {
        return price._value;
    }
}