Global Golf via eBay offers the Nike Method Core Drone 2.0 Mallet Putter in Left-Handed/Standard for $49.99 with free shipping. (A Right-Handed/35" model is available for $5 more.) That's the lowest total price we could find by $57. It features a polymetal grooved head and Opti-mass weighting.
Dick's Sporting Goods offers the Nike Vapor Flex Hybrid Left-Handed Golf Club in Stiff or Regular Flex for $89.98 with free shipping. That's the lowest total price we could find by $26. It features a Mitsubishi Diamana S+ Blue Graphite shaft and 4H loft.