I buy it by the gallon, usually on line, by searching for sales and/or free shipping. Last time I had to buy two gallons to get free shipping, so combined an order w/ a friend. While I do agree about keeping LQS open, this is an item I'd rather buy less expensively, if possible, so I have $ to spend on fabric.
Of course, it's also available locally @ the Mennonite store for less than $30...