Why are bottles like Eagle Rare, Weller, Blanton’s, and Pappy Van Winkle so pricy, and so hard to find? Credit: Food & Wine / Blanton's Bourbon / Getty Images / Buffalo Trace DistilleryThere are whiskeys you can easily find at your local liquor shop, and then there are allocated bottles, those often unicorn liquids whose availability is strictly limited. Of course, you can often acquire allocated whiskey on the secondary or gray markets, but the…