I'll tell you where not to get a battery: Walmart.
I needed a new battery very early one Sunday morning about a year ago & Walmart was my only option. Their Everstart batteries just aren't up to the heat, vibe & cranking demands of our XBs, and it's failed on me twice in the year since I bought it.
To Walmart's credit, they replaced the battery no-charge both times, but I certainly won't be going back a third time!