I bought this one on-sale last year as I was always running low of power on my iPhone. I initially looked in a competitor’s shop for a similar power-bank and they started at $80.
It’s quick to Charge and hold’s the charge for Month’s (if you store it away) and it’s very affordable.
I highly recommend it for the Sale price but I’d still pay the RRP if I hadn’t noticed it on-sale. I might buy these as Gifts as they’re compatible with most Smartphones!