Romoss Direct via Amazon offers its Romoss Ultra-Slim 2,800mAh Extended Battery Charger Case for iPhone 6 Plus / 6s Plus in Grey or White for $22.99. Coupon code "ROMOSSEC" cuts that to $18.39. Plus, Prime members bag free shipping. That's the lowest price we could find by $8, although we saw it for $2 less in September. This silicone case allows charging and syncing with your original Lighting cable and features an automatic shutoff. Deal ends November 6.

Note: The same code drops iPhone 6 cases to $17.59.