Lightning deals have a limited number in stock and once they are sold out, they are gone. And sometimes this happens in under 1 minute! However, I do encourage you to “join waitlist”.
When you “join the waitlist” you are notified if an item becomes available. Many times people add items to their carts during lightning deals, and then decide not to purchase them. This frees up an item for someone on the waitlist.
Yesterday my friend joined the wait list for a LEGO item and was told she was over 500 on the list. But guess what? She ended up getting the item, at the Lightning Deal price!
Once you are on the waitlist, keep Amazon open and you will get an alert if the item becomes available for you. Then you have a limited time to complete the transaction.