As of now, this 10,000mAh fast-charging powerbank is selling as low as $19 on Amazon, its all-time lowest from its usual $129 ...

Designed to work with Walrus Audio's modular pedalboard power supplies, the Canvas Power USB can be used for a wireless rig ...

But the cells used in these units aren't exactly the best. Eg. "Hoverboard" or "E-cigarette" quality particularly the ones that make the news. I'm sure they'll dump power fast enough for a jumpstart ...