Amazon offers the Oregon Chai Sugar-Free Chai Tea Latte Concentrate 32-oz. Box 6-Pack (192 oz. total) for $15. Check out via Subscribe & Save to drop the price to $14.25 and bag free shipping. That's about $4 less than you'd expect to pay in local stores. Each box makes a half gallon of chai tea latte when you add milk. It's sweetened with Splenda.
Be sure to cancel Subscribe & Save after your order ships to avoid being billed for subsequent shipments.