The items shown in this display case are the only products we currently have available.
Currently we can only sell the products shown in this display case.
季節外れ = out of season
その商品は今季節外れなので、ご用意できません。
That product is out of season now, so it's not available.
売り切れてる = sold out
その商品は今売り切れていますので、ご用意できません。
That item is currently sold out./We're sold out of that item.