Bats are an expensive purchase, and they do occasionally break.  Assuming the bat didn't break from abuse, you can expect the manufacturer to replace it, IF you purchased it from an authorized dealer.  Simply having a receipt won’t do you any good if that receipt isn't from an authorized dealer.  To ensure a valid warranty, go to the manufacturer's website to verify that the seller is an authorized dealer.  

Great prices can sometimes be found from sellers who are not authorized dealers, and you may decide going without a warranty is worth the risk.  Just don’t pay the going rate for a bat and not get a warranty.

Also see the Equipment Guidelines page for further purchase considerations.