this is $30, i'd highly recommend it.
https://www.amazon.com/dp/B01CZV9FUW/ref=cm_sw_r_cp_api_HbWIxbRVRZ3VP
I have an anker 10000mah one, pretty good and compact. https://www.amazon.com/gp/aw/d/B01CZV9FUW/ref=mp_s_a_1_2?ie=UTF8&qid=1468580985&sr=8-2&pi=SY200_QL40&keywords=anker+powerbank+quick+charge&dpPl=1&dpID=31gCZcX7ZgL&ref=plSrch - this is the one with quickcharge 3.0, the normal one is only 19$
https://www.amazon.com/gp/aw/d/B00Z9QVE4Q/ref=mp_s_a_1_2?ie=UTF8&qid=1468581011&sr=8-2&pi=SY200_QL40&keywords=anker+powerbank&dpPl=1&dpID=31rGxoDUwpL&ref=plSrch - 13000mah one, no quickcharge.
I have this and it's great. Usually can get 2 maybe 3 charges.