Staples offers the TP-Link 10,400mAh Power Bank Battery Pack, model no. TL-PB10400, for $24.99. (Amazon offers it for the same price.) Plus, Staples Rewards members receive free shipping. (Not a member? It's free to sign up.) That's the lowest total price we could find by $25. It features 1-amp and 2-amp USB outputs. Deal ends November 29.