When I go to a new liquor store, I look for a liter bottle of Jamison. If it's $40, I laugh in the face of the clerk and walk out. If it's $35, I'll maybe buy one thing and never come back. If it's $28, I'm a customer for life. It's important to have a fixed-cost good that you can use to gauge whether or not the place you're shopping is grossly overpriced, but it's difficult in most situations. A liquor store is not one of them.