U.S. Parts Outlet via eBay offers the Optima 8171-767 YellowTop Deep Cycle & Starting AGM Battery, model no. DS46B24R, for $145.79 with free shipping. That's the lowest total price we could find by $21, excluding the mention below. It's compatible with Toyota Prius models with a smart key option.
Close prices: Amazon offers it for $147.05 with free shipping.