Did Amazon rip me off?

In August I ordered a text book through Amazon for 80 dollars. They recently emailed me saying they had to cancel the order because it was out of stock. They said I could reorder it with them but I don’t even want to anymore. I just want my 80 dollars back.. What can I do to get this back or some type of credit? I’m really tight with money now so I’m sort of freaking out!