Anker Powercore II 20000 Dual USB Powerbank 34.99
Found this steal for a high quality unit. Going to Hawaii in a few months and this will help the 12 hour flight. EDIT: I found this has gone on sale for 30 on black friday, but still a good price for those who missed the BF deal.
Redeem the coupon at the promotions selector (it shows a buy 1 get another product % off.... once you select all promotions, you see the price.
I know its pricier than other units but its so good quality.
Also picked up a Anker 60W 10-Port USB Wall Charger for 27.99 via this link. (deal is not on page but go to promotions as well.)