(expired: sold out)
RavPower 30,000mAh battery pack with one 90W USB-C power delivery port and one QC 3.0 USB-A port. Add one to the cart for $80, apply coupon code RR232 in the cart, then proceed to checkout. The price is $56 with free shipping.
Charges with a 60W USB-C power adapter (not included). They sell one for $24 with coupon RC33, and must be purchased in a separate order since RavPower.com accepts one coupon per order.
Understand your risks when bringing this to an airport. The 30,000mAh battery exceeds the limit allowed to carry on an airplane. If this device is packed in a carry-on bag, you may be denied entry through security at most airports worldwide.