Some Grocery stores will give them to you for free, because they are just taking up space in their backrooms since now milk always comes 4 gallons to a card board box.....They don't use the crates anymore. Worth at least asking around locally while grocery shopping, worst they can say is no.
Publix, Kroger and Ingles all told me no. I figured a more small town store may give them away. I don't have any small time grocery stores around me though.