AvailabilityChangedArgs.cs

public class AvailabilityChangedArgs : EventArgs
{
    public bool SoldOut { get; }

    public AvailabilityChangedArgs(bool soldOut)
    {
        SoldOut = soldOut;
    }
}

Product.cs

public class Product
{
    private int _available;
    public event EventHandler<AvailabilityChangedArgs> AvailabilityChanged;

    public Product(string name, int coins, int available)
    {
        Name = name;
        Coins = coins;
        Available = available;
    }

    public string Name { get; }

    public int Coins { get; }

    public int Available
    {
        get
        {
            return _available;
        }
        set
        {
            _available = value;

            AvailabilityChanged?.Invoke(this, new AvailabilityChangedArgs(Available <= 0));
        }
    }
}

ProductView.cs

public class ProductView : MonoBehaviour
{

    [SerializeField]
    private Text _code;

    [SerializeField]
    private Text _name;

    [SerializeField]
    private Text _coins;

    [SerializeField]
    private Image _panel;

    [SerializeField]
    private Sprite _productAvailableTexture;

    [SerializeField]
    private Sprite _productUnavailableTexture;

    private Product _product;

    public Product Product
    {
        set
        {
            RemoveListeners();

            _product = value;

            AddListener();

            _name.text = _product.Name;
            _coins.text = "" + _product.Coins;
            UpdateAvailabilityIndicator(_product.Available <= 0);
        }
    }



    public string Code
    {
        set { _code.text = value; }
    }

    public ProductView Create(Transform parent)
    {
        GameObject go = Instantiate(this.gameObject, parent);
        return go.GetComponent<ProductView>();
    }

    private void AddListener()
    {
        _product.AvailabilityChanged += OnAvailabilityChanged;
    }

    private void RemoveListeners()
    {
        if (_product != null)
            _product.AvailabilityChanged -= OnAvailabilityChanged;
    }

    private void OnAvailabilityChanged(object sender, AvailabilityChangedArgs evt)
    {
        UpdateAvailabilityIndicator(evt.SoldOut);
    }
    private void UpdateAvailabilityIndicator(bool soldOut)
    {
        _panel.sprite = (soldOut) ? _productUnavailableTexture : _productAvailableTexture;
    }
}