Teaching kids how to run businesses.

A week before black friday my son ordered his birthday presents. All items were in stock and ready to go... Now the delivery is delayed, things are no longer available and some things wont even be restocked. Its been over 2 weeks.... and somehow only now you realise you dont have some of the stuff...and wont be stocking it agian... how does this work? How do I explain to him that the stuff he bought with his vouchers, which he saw me buy, not only are delayed but also wont have everything he actually bought?